Which puffer to select for your first fish from this family is not a simple choice. The whole family is erratic in appearing in local fish stores (LFS). To make matters worse, the true freshwater (FW) puffers are less often seen than the brackish members of the family in my area – no matter what the store labels them. But due to the simplicity of FW over brackish water (BW), I suggest that this might be the best place to start

Colomesus asellus the South American FW puffer.

The South American FW puffer, Colomesus asellus (1), is found in the wild in the area of the Amazon system in Brazil, Colombia, and Peru. In the hobby it is most often called the SAP, for the South American Puffer. The fish in your local shop will be imports from there, as these fish are not yet bred in captivity. This family has multiple freshwater species. These are secondary freshwater fish, meaning the group originated in the sea, and through geologic time their ancestors adapted to totally FW in South America, Asia, and Africa. As they are secondary FW fishes, they are fairly adaptable to water parameters, and should adapt well to your local water supply so long as it is suitable for keeping fish at all. This gives you a break in tank maintenance, since no water modifications are required.

The South American FW puffer is neither tiny nor jumbo, reaching about 3 inches (standard length, without the caudal fin) if not crowded, and fairly round-bodied. The real captive size of this species is uncertain. That 3″ figure is in part from my experience, in part from a number of other hobbyists who have kept this fish from multiple different purchases and under varying conditions. One fairly recent reference (2) gives the length as 11 cm. (~4.3″), and Fishbase gives 14 cm TL (~5.5″) as the maximum collected specimen size. It may well be that we are not doing the best possible job of keeping this fish in captivity. Even if the ’91 reference is TL rather than SL, the caudal fin is not that big a proportion of total length. We need to grow our SAPs a bit larger. If I ever the opportunity again, I would like try some varied strategies on this fish, with more current and perhaps higher oxygen levels than I have had in the past. All that presupposes that the reported measures are accurate. That is not always the case. Until fairly recently, the relatively new (to science and to the hobby) dwarf puffer was reported as growing to 15cm (5.9″), while in fact they only rarely exceed 2.5cm, ~1″.

In the wild SAPs inhabit the main channel much of the time, so are accustomed to currents and are strong swimmers. The reference noted on the drift of larvae in the river (2) has some interesting ideas on the presence of small larvae in the main channel and in the flooded lakes during the wet season. If you are conservative and want to keep only a single fish, a 15-gallon tank will serve, although a 20 would be my choice for a permanent home. Either the long or high style is fine, although the long form might be best from the fish’s view with its larger footprint. Good current, and resulting high oxygen levels, are quite important for these fish. Plants should be restricted more to the back and very ends of the tank, and the strongest currents along and parallel to the front glass of the tank for relatively clear swimming space for the maximum distance possible.

These fish will appreciate sturdy and hardy plants if you have any plant-growing skills. They like a visually complex environment and will explore routinely. Many puffers appreciate caves or other overhangs for naps and sleeping, so a couple (to allow choice) of these would be good as well, but dense overhanging plant groups may very well serve the same purpose, and have for me. If you are not a plant grower, rocks and driftwood and artificial plants will serve that function. As puffs are high-personality fish, and South Americans are cruiser-hunters and active fish, a singleton will not be a boring tank in any way.

They will recognize you and beg for food just as do many other pet fish. As these fish are among the mildest in the family, tankmates are a possibility, but not without risk. If you take the live plant path, don’t count on plant-maintenance live crews such as Amano or other algae and debris-grazing shrimp, or snails. Both of those groups are prime puffer food. Even Otocinclus species cats are not guaranteed safe. Dwarf plecos such as Peckoltia and the dwarf Panaque species may be a bit safer if plenty of hiding places are provided (rock piles or bogwood tangles), in part because those fish tend to be more nocturnal. The Peckoltia cats cannot groom small-leafed plants very well in my experience. They are just not built for it – their swim bladders, if present, are not sufficient for the job. A moderately lighted tank with low to moderate-light plants will make algae control much easier. Do remember that additional specimens will need more water volume. Adding more fish in a 15 is not the best for the puffer, and is not recommended.

As these fish tend to be tolerant of conspecifics (more of the same kind of fish), you can keep a trio if you select a larger tank, say a thirty-long (36″) or a fifty, or perhaps a quartet in a forty-long (48″) or 55 gallon. Remember the suggestions above about a visually complex setup (from the fish’s view, not yours) with broken sight lines through the tank and several refuges (more than the number of fish). I know these tank sizes may seem quite out of proportion to folks who have only kept community tanks previously. Puffers tend to be poor community fish. They are active, may be nippy, and have teeth and jaws that are fully capable of taking a chunk out any other fish sitting around or swimming by. This particular species is not very aggressive – for a puffer. That does not mean it is always trustworthy. There is also a very wide variation in the aggression and territoriality shown by particular specimens within any species. And like goldfish and Oscars, they also appear to be always hungry – which does not mean they always need to be fed. This does mean that they are more than willing to taste anything that appears edible – including tankmates. They are not fish-eaters by nature, just curious and ready to try.

One reason for suggesting the spacious quarters is that these are messy fish. Think of miniature Oscars or goldfish. Nearly constantly active without being hyperkinetic (although some individuals are), they need space and volume to adapt well to captivity and to grow to normal size and configuration. They are also, like Oscars and goldfish, messy eaters. The nature of their mouths and fused teeth results in wasted bits of food left in the tank water and gravel. More water volume gives you a higher margin of safety, when paired with good mechanical and biofiltration and regular water partials. These fish do need high quality water with zero unoxidized metabolites (ammonia and nitrites) at all times and with low nitrate levels. Good tank maintenance is very important to these puffers and actually to the family in general.

One of the strong recommendations for this puffer is appearance. They are rather bumblebee-like with alternating irregular bands of dark brown to almost black, with intermediate bands of yellow. Their bellies are white when they are happy and healthy. Gray or sooty-looking bellies may be a symptom of stress if persistent. Overall they can be one of the most attractive puffers. Unfortunately, not all specimens seen have good clear colors. Some are duller and a less sharply marked. You cannot always tell whether the stressed fish in the dealer’s tank will brighten up fully or not, but if any of the fish in the LFS group show bright clear color, the odds are the group will brighten up under good care. The ones that do will keep their bright coloring for years. As their lifespan should easily exceed ten years in your care, possibly substantially longer, this is no small thing. Don’t be concerned when their morning colors are blurred or faded, many fish in this family show general muddying and paling of color and markings while they sleep. They should brighten up soon after they are awake and swimming about.

Newly purchased fish need quarantine – this can be in their permanent tank if it is pre-cycled. Puffers generally do not come in to the LFS in the best of shape. They have been overcrowded (resulting in nips and bites), underfed or improperly fed (weight loss and/or malnutrition), and subjected to multiple water changes without proper cautions (still more osmotic stress). Do not buy fish with severely concave bellies. Flat bellies may be okay – South Americans are not as chunky as many puffs even when well fed. After eating they may show a bit of a belly bulge, but seldom to the extreme some of their relatives may show. Ich is readily treated in my experience by salt and heat (I use one teaspoon per gallon actual volume and raise the temperature to the low to mid-eighties Fahrenheit). Watch for signs of oxygen lack while at the warmer temperature, Velvet is a bit more difficult and may be seen in the LFS at times. I tend to leave such infected fish in the store. Once through adaptation to you and your care, they are quite hardy so long as you maintain water quality.

Feeding is not a problem, but does require live and frozen foods. Snails and smallish crustaceans are their natural prey. Freeze-dried krill is another good food, but is best pre-soaked prior to feeding. Frozen or live bloodworms (midge larvae) are readily taken. Frozen shrimp (shell-on) from the grocery store may be cut to smaller pieces while frozen and stored for individual meals. All frozen foods should be thawed prior to feeding. “Juicy” hobby preparations such as frozen bloodworms may be thawed in a brine shrimp net under cool water to purge the excess high-protein liquid before the food is added to the tank. Very small new puffers may be started with live adult brine shrimp, preferably with the introduction of thawed frozen bloodworms at the same time. I am not too convinced of the nutritional value of live brine shrimp as a staple without extra handling and gut loading, but they are great for getting new pets to eat. Pairing a readily accepted food like this with a more nutritious food may convince the puffers that the bloodworms or other “new” and unfamiliar food can be tasty too. Other LFS types of frozen food such as mussels, clams, squid, etc., are learned as well. But a substantial part of any hunter type’s diet needs to be crunchy foods which will help wear down the puffer’s constantly growing teeth. In my care, this species’ diet is at largely cultured snails. SAPS are the worst in the family for tooth/dental plate overgrowth. That implies that they feed almost exclusively on hard-shelled prey in the wild.

These are very attractive, intelligent, active fish, which are long term quite easy to maintain. They are among the longer-lived of the “pet” fish with enough personality become real pets, but being basically a schooling fish (although seemingly without the depression and timidity seen in most other schoolers if alone), they are not quite as high-personality as some of their brackish relatives. If you want to try something other than community fish, a single puffer or a group of compatible puffers may change you attitude toward fish tanks, and will provide many hours of pleasure for very few hours of work invested.

For more information, see also Introduction to Puffers:

Introduction to Puffers:

Plus the earlier note on raising snails for puffer feeding:

Raising snails for puffer feeding


1. Fishbase species summary

2. http://horizon.documentation.ird.fr/exl-doc/pleins_textes/cahiers/hydrob-trop/43866.pdf

Robert T. Ricketts, a.k.a. RTR


First Freshwater Puffer? Try South America.
By: Robert T. Ricketts



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