julho 30, 2011

How to breed perfect guppies. (Como reproduzir perfeitos guppies)

Guppy guru Derek Jordan offers advice to experts on how to keep and breed top quality guppies

Copyright © Neil Hepworth
There is a popular belief that Guppies are a hardy fish which can be neglected, yet still flourish, and that they are a fish for the beginner. Now although many fishkeepers started with Guppies, over the years the species has encountered some quite bad press, mainly due to overbreeding and inbreeding issues. 
However, there is absolutely no reason why you cannot have a perfectly healthy tank of these stunningly coloured fish. As Guppies are easy breeders, with a little care you can optimise your chances for a healthy, vibrant stock. 

Getting down to basics
A breeding set-up should be designed for easy maintenance, especially as chances are you'll end up with loads of tanks! I keep my breeding tanks in the bare mode, so no plants or gravel. 
Small tanks will suffice: 25 l./5.5 gal. for a breeding trio and 36-45 l./8-10 gal. tanks for growing on. As a rule of thumb, allow 2.5cm/1" of fish per gallon to allow your fish to achieve their full potential. 
Some enthusiasts opt for higher stocking levels, which is fine if you carry out more frequent water changes. Don't push your luck as you could end up with stunted, poor quality fish.
As for filtration, I opt for air-driven corner filters or sponge filters with plenty of airflow. And I mean plenty, such that the water above the filter looks like it is boiling. 
Such a strong flow serves one purpose; it forces the fish to develop strong muscles, especially in the caudal peduncle. This helps the delta varieties hold their tails in a more natural way and not look like the tail is too heavy, making the fish looks somewhat bent.
Ideal water parameters are pH 7.2 (normal range 6.8-7.8); 8-12 degrees GH (normal range 4-20 degrees GH); and a temperature for fry of 25.5 degrees C/78 degrees F; juveniles (four to eight months) of 24.5 degrees C/76 degrees F, and adults somewhat cooler at 23.5 degrees C/74 degrees F (normal range 10-29 degrees C/50-85 degrees F). 
A Guppy needs 12 hours of lighting each day, best provided using 30-40W fluorescents mounted above your tanks. Don't be misguided into thinking that intensity matters. 
Duration is far more important, and a simple timer will ensure that the lights are turned on and off at the right time.

Care and maintenance
Guppies are omnivores, so offer as wide a range of quality flake food, live and frozen foods as possible. It is also better to feed small amounts every few hours than one gigantic feed. 
Frozen and live food are digested easier than flake food, so can be fed in larger portions. As a guide, if your fish do not eat all the food you put in the tank in two minutes, chances are you're overfeeding them - or they could be ill. 
If you overfeed your Guppies, the excess food passes through the gut without being properly digested and will foul the tank. Try to avoid feeding a diet rich in protein as this can cause constipation, causing a build-up of toxins in the fish's gut. 
Which leads me to the point that fish create waste, and this waste creates both good and bad bacteria. If waste builds up within the tank, eventually the bad bacteria will outnumber the good and the water conditions start to fail. 
Correspondingly, your Guppies' fins and health will deteriorate. Regular water changes are a must. I carry out weekly changes of 25%.

Know your strain
Before you attempt to breed Guppies, you need to understand the characteristics of your chosen strain - each is unique. 
This can be tricky if the person you bought your fish from does not know its genetic make-up. However, all is not lost as close observation and the keeping of breeding logs will reveal much.
The first step is to note all the characteristics of your stock. For instance, does the colour have a uniform look or is it more intense in specific areas? What about fin shapes? Find out what the ideal shape should be. 
Fellow enthusiasts are always a good source of information. Find out if your strain carries the traits you want on the X- or the Y-chromosome. The Internet can be very useful in helping you trace the genetic make-up of your fish.
Obviously if you have a specific goal, eg. solid black fish, this makes it easier to organise your tank space and select the fish you intend to keep out of each litter, ie. as much black in the body, or even a particular dorsal or caudal shape.
Never, ever keep just the one pair of breeders: disease happens, no matter how careful you are, and you do not want to put those years of hard work in jeopardy by losing just two fish. Ideally, aim for two or three trios in separate tanks.

Keep those records

Your breeding log should have the following information:

Identity: Give each breeding pair or trio an identity number, so your first pair is number 1, your second number 2 and so on. This allows you to trace the lineage and any crosses that have been made.
Sex: M or F for male or female.
Colour/strain: eg. half-black red delta or yellow snakeskin.
Generation: Start with P for parentage, followed by F1, F2 etc.
Cross: Are the fish being bred brother to sister (siblings), parents to daughter or son (backcross), or to a genetically related strain (outcross)?
Parents: What was the identity number of the parent fish?
DOB: Date litter was dropped. This is useful to work out the age of fish for breeding and to track their progress for finnage and colour development, which varies according to strain. 
Breeders produced: Did they produce any litters with potential breeders?
Notes: Allow plenty of room for observations about when the fish started to sex out, ratio of males to females, growth rates, etc.
Always mark the tank with the ID number and the date the litter was born. Masking tape is good as you can easily remove this and attach it to the fish's new tank if you move it.

Line breeding
The problem with successive inbreeding is that each generation loses some genetic diversity. Line breeding helps overcome this and keeps a strain true. 
Basically it combines inbreeding with a crossing from a related line every few generations, ensuring healthy Guppies for years.
The most common method is to break your strain into two lines for inbreeding. Then after three generations, cross the lines. A simple illustration of inbreeding is:

Line 1 Line 2
P1 M F P1 M F
F1 M F F1 M F
F2 M F F2 M F

Cross Line 1 F2 female (F) with Line 2 F2 male (M), and Line 2 F2 F with Line 1 F2 M.
Guppies are typically four months old before they can be bred, so to repeat the above for three generations would take about 12 months before your first cross. Also the more lines you run, the more diversified your gene pool will be.

Out-crossing
This refers to the mating of two unrelated Guppies. While inbreeding reduces the variations of your offspring and line breeding helps keep your gene pool intact, out-crossing corrects or adds a gene to your strain. 
For example, you may want to get a bigger dorsal fin, improve the colour or rectify a defect in the caudal fin. Or you may even want to create a totally new strain. 
Having said that, out-crossing is best not attempted by a novice for if you get it wrong, you could lose the strain traits altogether.
With out-crossing, it's critical to ensure strains are compatible - some colour strains mix, others don't. For instance, crossing a variegated snakeskin with a half-black red results in a very mixed-up Guppy. You really need to keep the original strains pure. 
Out-crossing demands plenty of tank space and patience to carry out the required backcrosses to end up with the results you want. You'll need to use established strains whose genetics are stable, meaning that all offspring look identical. 
Finally, try the cross both ways - female to outcross strain and male to outcross strain; you may not know whether the trait you want is X- or Y-chromosome linked.

Backcrossing
This is where you breed, say, the male of a strain that you want to rectify a problem back to one of his daughters from the outcross, or the female of the strain back to her son from the outcross. 
The aim is to restore the strain to its original format, but with the trait fixed. 
You may have to perform this a few times. The way to check is if the sibling-to-sibling mating produces replicas of the parents with the trait fixed.

Who was first?
The Guppy takes its name from Rev. Robert John Lechmere Guppy, a conchologist, geologist and clergyman living in Trinidad. 
Although he is credited with discovering the wild Guppy in 1866, Spaniard De Filippi found the fish in Barbados in 1862 and labelled it Lebistes poeciliodes. 
However, even earlier in 1857 and 1858, amateur German biologist Julius Gollmer found Guppies near Caracas, Venezuela. He sent these fish to the Imperial Prussian Academy of Science, Berlin. 
The ichthyologists were apparently not impressed, gave Gollmer only a small reward and then promptly filed the specimens in its archives. There they remained until 1859, when Wilhelm Karl Hartwig Peters, head of the ichthyology department, wrote a scientific description of them. 
Unfortunately, the jars were not well labelled and he only described the females as belonging to a new species, Poecilia reticulata. Some time after 1866, the males were found and labelled Giradinus guppyi. The females later adopted the name of the male counterpart.
The scientific name has undergone a number of revisions over the past 100 or so years, finally settling on Poecilia reticulata (Rosen and Bailey, 1963). Rosen and Bailey also included Mollies in the genus. 

The pioneer
Great Britain's pioneer in the fancy Guppy world was W. G. Phillips, born in 1883. During the Second World War, he sold his excess Guppies to a shop in London. 
Some months later, he returned to find that a few remained and had bred, with some of the offspring having unusual tail shapes. He took these home and over the next few years, perfected the now familiar Coffer Tail shape.
Phillips created the British Guppy judging standard, from which all subsequent judging standards have been drawn. He also developed and sent overseas the English Leopard Guppy or English Lace Guppy, which may have been the original source of all Snakeskins. 
Phillips won over 500 awards for his Guppies, and his house in Kenton was a shrine to the enthusiast. He was not a secretive man but freely shared his Guppies and ideas, leaving behind a huge legacy today.

Did you know?
The word 'Poecilia' means 'variegated' and 'reticulata' refers to the lacy pattern that is formed by the overlapping scales on the Guppy's body.
The Guppy has been called the Missionary fish as it has converted many to the hobby.
The Coffer Tail Guppy got its name from the fact that it resembles the South Wales miner's shovel.

Published: Derek Jordan

julho 22, 2011

Como reproduzir o Tetra-Neon

How to breed neon tetras

How to breed Neon tetras
Copyright © MP and C Piednoir, Aquapress.com
Breeding expert John Robertson describes how he raised Neons – one of the world’s most popular and recognisable tropical fish.
I had not kept Neon tetras for almost 40 years. They were the first egg layers I ever had in my first 60cm/24” tank — and I had not kept them since.
Yet I have kept Cardinal tetras many times while looking down my nose at Neons. Those Cardinals have much to answer for…
However, I recently found myself with another 24” tank and a dozen Neons. It was filled with rainwater and leaf litter and heavily planted with Java moss and Indian fern. Sitting in the darkest corner of my fish house with a feeble light above, its murk made those Neons look absolutely gorgeous!
The reflective blue-green of that almost luminous stripe set off against red underparts made for a stunning spectacle in the dim light as the little fish danced and darted about. The tank had a DH of less than 1, pH of 5.5 and temperature of 24°C/75°F.
Within a couple of weeks they were spawning every day. I discovered later that Neons can breed from 12 weeks old, which is about the age of most we see for sale. Occasionally a baby would survive and I would spot the tiniest Neon, just beginning to get its colour, peeking out cautiously from the undergrowth.
I decided to try and breed them properly — and my first attempt was the lazy way that always works so well for me with killies and many other species. I just removed the adults and waited!
Sure enough. Within a couple of weeks a handful of baby Neons appeared but, after three attempts, there were never any more. 
Going traditional
Then I tried the traditional method of setting up a bare 30 x 20 x 20cm/12 x 8 x 8” tank with a natural mop of Java moss and fresh rainwater. I darkened the tank, added a well conditioned pair and settled back to observe.
I never saw them spawning and no fry resulted from that first attempt. With later efforts I left the parents together for five to seven days and a few fry were once produced, but they were nothing to write home about. Frustratingly, in the original tank the adults had continued to spawn every day...
I decided to set up a new tank; this time 75cm/30” long, again with rainwater, and with a 2.5cm/1” deep layer of freshly collected oak leaves and one bush of Java moss. I introduced two pairs of adult Neons and watched for about 14 days.
Two things happened. First the water began to go brown and more acidic as the oak leaves softened, and the DH became less than 1, pH less than 5, temperature was 26°C/78°F. The fish took about a week to feel at home in the new tank, but then began to spawn every morning as the room lights were switched on.
The water, tannin stained, became darker and darker and I removed the adults at 14 days and waited. After about a week later I peered into the darkness and spotted a single fry moving hesitantly through the leaf litter. In subsequent days I spotted more and more and I added newly hatched brineshrimp, which they relished.
After about a month I was counting more than 30 fry, and in total this attempt produced about 100 young.
I’m not sure that the pH is critical, but the darkness is. The eggs and fry are susceptible to light, but I believe that the brown water and leaf litter also hid the eggs from the hungry adults which I had fed only sparingly in the breeding tank.
Encouraged by my success I decided to use a similar but larger set-up to try and spawn Congo tetras, but within 24 hours of placing them into the acidic conditions the adults had died.
The Neon tank had acidified over several days and the fish had acclimatised during that period.
However, with the Congos I foolishly let the tank ‘mature’ for a couple of weeks and the fish succumbed when placed into conditions very different to their natural home.
Young Neons colour up at about four weeks and under good conditions are large enough to sell at 12 weeks, but your dealer won’t thank you unless you gradually change the water back to tapwater. I did so over about four weeks and had no ill effects.

Do some babies grow faster? 
One breeding observation still puzzles me. Up to eight weeks after I first spotted fry in the breeding tank, tiny colourless babies still continued to appear. Yet the first baby Neons were already large enough to go back to their parents’ tank and become part of the crowd.
I don’t think it possible that the ‘older’ babies were already breeding as this had been a continuous process, a few tiny babies appearing each day or so. The only reasonable explanations are that some grow much faster than others, or that some eggs experience delayed hatching —  as do many killifish.
The former theory is most likely, as the latter would surely have been noted earlier by better observers.
I’m speculating that in nature some baby Neons stay small and undeveloped, hiding in leaf litter so that if their body of water becomes cut off and evaporates, killing their faster growing siblings, they can survive in tiny amounts of water until the rains come.
I have noticed similar situations with Apistogramma and Ctenopoma, and can’t think of any other explanation.
Published: John Roberston 18 July 2011

julho 20, 2011


Scientific American


Bifocal Fish Sees Differently above and below Water Line
A fish (Anableps anableps) that keeps its eyes half submerged has specially adapted pupils and retinas to see clearly both above and below the water. 
Christopher Intagliata reports
July 20, 2011



Listen to this Podcast: 

http://podcast.sciam.com/daily/sa_d_podcast_110720.mp3


“Hey, four-eyes!” That playground taunt is more accurate when applied to Anableps anableps—a fish related to the guppy. It lives in the brackish waters of mangrove swamps in central and South America, and hunts for food at the water's surface... its bulging eyes submerged halfway. Which poses an evolutionary problem—should those eyes be attuned to the greenish light streaming through the mangroves? Or the yellowish rays drifting up through murky water? Well, these fish eyes see both.
Anableps doesn't actually have four eyes—just the usual two. But each eye has two pupils, one above water, one below. And each pupil sends incoming visual info to a different side of the fish's retina.
Cones in each half of the retina are adapted to produce different light-filtering pigments. So cones hit by underwater rays are primed to sense longer-wavelength yellow light. Cones hit by daylight are sensitive to shorter-wavelength green light. The finding appears in the journal Biology Letters. [Gregory Owens et al., "In the Four-Eyed Fish (Anableps anableps), the Regions of the Retina Exposed to Aquatic and Aerial Light Do Not Express the Same Set of Opsin Genes"]

The entire arrangement makes it easy for this bifocal fish to spot a tasty bug flying above the water, or a bit of algae below. For when it comes to evolution, the ayes have it.

Are my plants eating my fish???
Are my plants eating my fish?
Copyright © Veledan, Creative Commons
Sounds ridiculous, but they could be, says Rupert Collins.
I'm sure that everyone will have heard of carnivorous terrestrial plants such as the Venus flytraps, Sundews and Pitchers, but did you know that there are also aquatic versions?
The Bladderworts (Utricularia spp.) are a varied group of aquatic plants, which possess a highly sophisticated mechanism to catch their food.

They have no roots, and the plants tend to creep or float on the surface.

They have traps comprising small bean shaped bladders, and the plant pumps water out of them until they are flat and curved inward under pressure.

Next to the trapdoor, bristles are present, which act as a trigger. If a hapless prey item (e.g. Daphnia) bumps into them, the trapdoor bends enough to break the seal and the walls spring back to their normal shape creating a vacuum, engulfing the prey within one hundredth of a second. The prey is then chemically dissolved and consumed.

But can they eat fish though? While most Utricularia have very small bladders, there are several species with bladders up to 1.2 cm, and they have been reported to eat fry, tadpoles and mosquito larvae.

So, while adult fish are not really at risk, certainly tiny fry could be eaten.

Utricularia are not sold frequently in the trade, but can be ordered from specialist aquarium plant stores,
or can sometimes be found as hitchhikers attached amongst floating plants such as Riccia.
Many have quite beautiful flowers, so might develop a following in the planted tank side of the hobby if there is sufficient demand. Some with interesting foliage have even been incorporated into nature aquariums.
Published: Rupert Collins, Tuesday 19 July 2011
http://www.practicalfishkeeping.co.uk

julho 16, 2011

by Neil Hepworth
The Red-bellied piranha: 
What a spoilsport!

http://www.practicalfishkeeping.co.uk
Published: Matt Ford (28 April 2011)

The facts really do spoil the more popular blood-chilling stories about piranha. Matt Ford reveals more home truths about the Red-bellied species.
Famed as a rapacious predator capable of rapidly stripping flesh from bone and a danger to any creature entering its waters the Red, or Red-bellied piranha (Pygocentrus nattereri, Kner 1858) is among the world’s most notorious freshwater fishes.
As a result, displays featuring this “bloodthirsty” animal are found in most public aquaria, and they have been part of many gruesome but fictional storylines.
Thankfully, informed captive maintenance of piranhas and their relatives has undergone a relative boom over the last 15 years and a number of websites and forums are dedicated to them. 
Many different species are available, but the majority are wild caught, costly and therefore beyond the means of most hobbyists. P. nattereri is, however, farmed in numbers, with coin-sized juveniles sold rather cheaply for a fish requiring specialised and ultimately expensive care.
For the enthusiast it makes an excellent aquarium subject, but proper thought and research are essential prior to purchase.
Water quality and tank size are the two main considerations, but maintenance is otherwise quite simple. Adult size is 30-40cm/11.8-15.7” so even a single specimen will need plenty of room.
A 750/800 l/165-175 gal tank would be minimum for a group.
These fish will not ‘grow to the size of the tank’ but can become stunted or even deformed if cramped for too long. Moreover, juveniles are more cannibalistic than adults, so don’t raise them in confined spaces unless very well fed. A typical lifespan is 10-15 years, so you need to make considerable investment in time and space for them.
Waste producers
Piranhas typically produce much waste, so one or more over-sized external filters is essential. If possible, buy units with in-built heaters or at least fit a sturdy heater guard as adults have damaged submerged equipment.
Sump systems also work well and the heater can be housed within it. If your tank holds below 1,000 l/220 gal, aim to change 30-50% of volume weekly.
Some hobbyists keep their piranhas in bare-bottomed tanks to be able to more easily syphon out uneaten food, but standard aquarium gravel or sand are both suitable substrates. Other décor is basically down to personal taste, but plants may be eaten, especially if the fish decide to spawn. Lighting is relatively unimportant.
It’s often said that wild piranhas hunt in voracious packs, but usually only juveniles group in numbers. Older fish exist in loose aggregations and form dominance hierarchies, so buy a single specimen or group of six-plus.
Piranhas are not exclusive carnivores, more accurately being described as opportunistic generalists. Their natural diet consists not only of live fishes but also aquatic invertebrates, insects, nuts, seeds and fruits. 


Fin feeders

Each jaw contains a single row of sharp, pointed, triangular teeth used like blades to puncture and tear, but equally to chop and crush. They also attack sick or dying fishes, feed on the fins of larger species and scavenge carcasses.
However, assaults on live animals entering the water are rare and mostly relate to accidental biting, or cases in which they’ve become trapped in small pools during dry periods, for example, when food is scarce and the piranhas are in unnaturally large numbers.
Such facts have mostly been ignored and while it’s true that big groups have been recorded to strip animals of flesh in minutes the true, less exciting, circumstances are normally omitted. 


Feeding in the aquarium

There’s no need for live ‘feeder’ fishes in the aquarium. These not only introduce the risk of parasites and disease but are not particularly nutritious unless well fed and quarantined beforehand.
Animal meats such as chicken or beef heart contain excessive fat and protein, some of which the fish are unable to metabolise.
Instead offer a balanced diet of frozen fish, shellfish, fruit, nuts, seeds, floating pellets, plus the occasional earthworm.

Can I breed them?
P. nattereri is easily bred and tank-raised youngsters, like the one shown above, are often available on eBay and other auction sites.
Sexual maturity is reached at around one year and at 10-15cm/4-6”. Unless you can find a sexed pair start with six or more and allow a pair or two to form naturally. In some cases spawning has been initiated by large, cool water changes, but in others it occurred naturally.
As males come into sexual condition they become isolated and excavate a patch of substrate using their mouth and caudal fin. Any plants may be cropped and the resultant nest is defended against other males.
Interested females respond by mouthing the substrate around the nest, and, when ready to spawn, both darken in body colour. Eggs and spawn are deposited in several batches and guarded by the male, sometimes assisted by the female. In the larger tanks multiple pairs may spawn simultaneously.
The eggs hatch in two to three days, with fry free swimming by the fifth.
At this point it’s best to syphon them into smaller 46-60cm/18-24” sponge-filtered tanks to prevent predation. Two to three meals of Artemia nauplii/microworm and water changes of about 10% volume are required daily.
The fry become increasingly cannibalistic, so should be moved to progressively larger tanks in batches of similar size.
Think carefully before taking on such a project, as you could end up with more than 1,000 young piranhas with little sell-on value.

Did you know?

Piranhas are an important food source for many human communities. They’re said to taste superb when grilled in a banana leaf and served with tomato salsa!

Blame it all on a stunt for the president...
According to Herbert Axelrod the flesh-eating myth began when the then American president Theodore Roosevelt visited Amazonian Brazil in 1913.
He was accompanied by several journalists and his Brazilian hosts organised several publicity stunts, one being that the president would ‘discover’ a river which would then be named after him.
A tributary of the río Aripuanã previously known as the río da Dúvida (river of Doubt) was chosen and is today still referred to as the río Roosevelt or río Teodoro.
When he arrived the Brazilian authorities had prepared a surprise. A stretch of several hundred yards had been netted off and for several weeks fishermen had been catching hundreds of adult piranhas and isolating them there.
They told the president that he and his entourage shouldn’t enter the water as they would be eaten alive by vicious fish.Naturally this news was met with scepticism, so a cow, quoted as being sick, old and in season, was introduced to the water. Some claimed its udders had been sliced open too.
This caused a feeding frenzy among the trapped, starving piranhas and newspapers were filled with stories of terrifying, flesh-eating fishes. 
However, to this day, there’s still no record of wild piranhas killing a human…


Tip
Want an aggressive predatory characin that doesn’t need a massive tank? The Hi-finned wolf fish, (Erythrinus erythrinus) is an excellent choice — particularly the colourful ‘Peruvian red’ form.
Keep a single specimen in a bigger than 100l/22 gal tank and feed it pieces of raw fish, prawn, mussel, gut-loaded crickets and earthworms.

A confused taxonomy
The name piranha is commonly applied to all members of the genera Pygocentrus, Serrasalmus, Pristobrycon, Pygopristis and Catoprion, but in truth is only applicable to the first.

Pygocentrus spp. are the fishes referred to as ‘piranha’ (caribe in Venezuela) in their countries of origin, with most of the others known as pirambeba. All are members of the family Serrasalmidae, a group currently comprising 16 genera, including other well-known ones like Metynnis, Myleus, Colossoma and Piaractus.
Their taxonomy is historically confused and continues to be revised, with Serrasalmus and Pristobrycon in particular presenting a number of identification problems. It’s beyond the scope of this article to discuss taxonomy in detail, but current knowledge suggests the existence of several clades (groups of closely-related genera) within the family, of which the ‘piranha clade’ contains all piranhas/pirambebas, plus the genus Metynnis (Ortí et al. 2008).
In terms of ‘true’ piranhas most modern enthusiasts continue to follow the nomenclatural system proposed by Fink (1993) in which only three species exist: Pygocentrus piraya (Cuvier, 1819), P. cariba (Humboldt, 1821) and P. nattereri.
While the identities of the first two remain in little doubt, Fink was unable to accurately diagnose P. nattereri, and it remains uncertain whether the species represents a single evolutionary lineage.
There’s also the mysterious P. palometa, Valenciennes 1850, described from the río Orinoco and still listed valid by some sources but generally regarded a nomen dubium (doubtful name) despite the occasional appearances on trade lists.
P. nattereri has proved difficult to identify. P. piraya and P. cariba are endemic to single river basins (the río São Francisco, Brazil and río Orinoco, Venezuela/Colombia, respectively) and possess morphological details allowing relatively easy diagnosis.
P. nattereri, however, was described from the Mato Grosso in Brazil but since been recorded throughout much of the Amazon basin (Brazil, Ecuador, Peru, Bolivia and questionably Colombia) as well as the río Essequibo (Guyana and Venezuela), smaller, coastal drainages in north-east Brazil/the Guianas, plus further south in the río Paraná (Brazil, Paraguay and Argentina) and río Uruguay (Brazil, Uruguay and Argentina).
Colour and patterning vary considerably, depending on locality and even within a single location. Colour is also known to vary with habitat type.
Fish inhabiting blackwater environments tend to be darker with less red/orange than those from clear or white waters, although blackwater populations are apparently rare.
Morphology and patterning in adults can vary in head and body shape, presence or absence of dark spots or reticulated markings on flanks and in fin pigmentation.
Such differences have led to some populations being described as distinct species, notably P. altus, Gill, 1870, from the Upper Amazon and P. ternetzi, Steindachner, 1908, from the río Paraguay.
Although piranhas are traded under both names, Fink studied more than 100 specimens from different parts of the Amazon and río Paraguay drainages and could find no consistent characteristics that could be used to define them according to origin.
Having found all three species non-diagnosable he decided to synonymise P. altus and P. ternetzi with P. nattereri, as the latter is the oldest available name for the group.
Although he admitted it was an unsatisfactory option, Fink’s classification is still in place. In 1997 he observed differences in body form between ‘northern’ and ‘southern’ populations of P. nattereri, but was again unable to obtain sufficient evidence that they represent different species.
Analysis using samples from many different localities may help to resolve some confusion, but the huge scope of such a study is likely to be a limiting factor.


Expert Q and A

Dennis Day has maintained piranhas in aquaria for more than 25 years and is co-administrator of the UK Piranha Forum.

Would you recommend the Red-bellied species to piranha newcomers? 
Pygocentrus nattereri is an ideal species to start off with.

What’s a good diet? 
Having raised several hundred P. nattereri I’ve found that newly hatched brineshrimp, alternated with microworm, was a good first food for fry.
At five to six weeks move to chopped bloodworm and crushed lance fish, going on to whole bloodworm and lance fish at eight weeks, along with earthworms as a protein.
Not until 20 weeks would I feed them on filleted fish, baby squid and raw prawns. I have never fed any of my fish with mammal meat.
At eight weeks you can get them on to pellet foods, such as Hikari Gold. Sinking pellet foods are not a good idea as they can get missed, trapped in décor and rot.

What are the chances of me getting bitten during any tank maintenance?
Virtually nil. You would have to be actively chasing the fish with your hand and trying to corner it before being attacked.
The only other way to get bitten is when netting the fish, placing your hand over the net or picking it up.

Given that the market is already flooded with them, what’s your opinion on the number of hobbyists breeding P. nattereri?
It’s always worth breeding fish, whatever the numbers available in the shops, but breeding P. nattereri on a commercial basis is not a good idea, as the outlay far outweighs the income.