Tropical Fish Hobbyist - December 2007

Pufferfish are among the most popular oddball fishes for freshwater and brackish-water aquaria. They are very entertaining fish, full

of life and constantly on the

move. Most also seem to be

quite intelligent, quickly

learning to recognize

their owners and often becoming tame enough to be hand fed. While puffers can be fussy about water chemistry and filtration, they are otherwise very adaptable and present the aquarist with few serious problems. In fact, the most widely traded species can be considered hardy and easy to keep. The icing on the cake is that pufferfish are very effective snail destroyers, and a tank with a pufferfish in it is a tank without pesky snails.

In short, puffers are cute, hardy, and useful fish for the home aquarium.

So why doesn’t every aquarist keep them? The main problem with puffers is their behavior; they may look sweet, but many are surprisingly temperamental, while others like to bite chunks out of the fins of slow-moving tankmates. Some species are very tolerant and accommodating while young, but become much more solitary and aggressive as they mature. Complicating matters further is that their social behavior can be unpredictable, even within species, and many aquarists have watched a seemingly well-behaved pufferfish turn into a psychotic killer overnight.

Is My Puffer Aggressive or Hungry?

Not all species of pufferfish have the same reasons for biting their tankmates. Some take nips out of all sorts of things because they’re hungry.

In the wild, puffers scour plants and rocky areas looking for their preferred prey, and in the process they take experimental bites out of anything that looks edible. Anyone who has kept pufferfish will recall their intensely curious behavior, swimming up and down plants and into caves as they examine every inch of the aquarium for food. While this is a useful behavior in their natural habitat, in captivity it can lead to bad habits like taking chunks out of plastic tubing, destruction of plants, and yes, fin-nipping.

However, other puffers, particularly the small freshwater species of the genus Carinotetraodon, fiercely defend their territories. They will attack tankmates not out of hunger, but out of anger.

Superficially, this would appear easy enough to work around: simply give the fish enough space that it doesn’t feel that its territory is threatened. In practice though, these small pufferfish are rarely kept in large enough aquaria for this to be a viable solution. After all, who’s going to set aside 40 gallons for a fish little bigger than a neon tetra?

A few puffers appear to be dedicated fin-nippers, viewing the bodies of larger or slow-moving fish as nothing more than “sushi on the go.” These fish are very difficult to keep in community tanks.