Pea puffer

An inch-long fish with opinions

My pea puffer watched me from the front glass every time I walked past the tank. I told myself it was affection. It was waiting to see if I was holding bloodworms, and when I wasn't, it went back to staring down a ramshorn snail.

Carinotetraodon travancoricus is also sold as the dwarf puffer or Malabar puffer. It comes from slow, weedy rivers and backwaters in Kerala and Karnataka in southwest India, and it lives in fresh water its whole life. Some shops keep it next to brackish puffers, but it needs no salt. Adults reach about an inch. With good care they live four to five years.

Nearly every pea puffer for sale was caught in the wild, and the IUCN lists the species as Vulnerable because of collecting. Buy fish that are eating well in the shop, and don't buy more than your tank can hold.

One in a 10, a small group in a 20 long

One pea puffer is comfortable in a cycled, heavily planted 10-gallon. Finish the cycle first, because puffers have no scales and handle ammonia badly. That single fish is the whole stocking. The 10-gallon stocking guide covers the other ways to use that tank.

For a group, start with a 20 long. Three is a good number there, and four can work in a well-planted tank. Keep one male with two or three females, or all females. Males have a dark line along the belly and wrinkle-like lines behind the eyes, and they get brighter yellow when they display. Females are rounder and spotted, with no belly line.

Plant the tank thickly. Stems, java fern, moss, and a few pieces of driftwood give each puffer a place where it can't see the others. In a bare tank the dominant fish chases everyone all day. If one gets bitten up or stops eating, move it out.

Heat, flow, and water changes

Set the heater around 77°F. They take 74 to 80°F and pH 6.5 to 7.5. A 50W heater covers a 10 in most rooms. Puffers hover and steer with their fins and they swim poorly against current, so use a sponge filter or a low-flow filter with a covered intake.

Frozen food and snail shells make a mess fast in a small tank. Change 25 to 30 percent of the water every week, siphon leftovers the same day, and keep nitrate under about 20 ppm. A water test kit shows you when the cycle is done and when nitrate creeps up.

Frozen food and snails

Most pea puffers won't eat flakes or pellets. Feed thawed frozen bloodworms, brine shrimp, mysis, or daphnia once a day. Thaw a small piece of a cube in a cup of tank water and feed what they finish in a couple of minutes. A full puffer has a slightly round belly. A hard, swollen one has been overfed. Skip feeding one day a week. The feeding guide covers portions for the rest of your tanks.

Give them small snails a few times a week. Ramshorn and bladder snails are the easy ones to breed in a jar or spare tank with some plants and a little fish food. Hunting snails keeps a puffer busy, and crunching the shells helps wear down its teeth. Puffer teeth keep growing. A puffer that never eats anything hard can end up with an overgrown beak, and a diet with snails in it usually prevents that. Mystery and nerite snails are the wrong snails here. Puffers pick at their antennae and feet until the snail dies.

Quarantine and tank mates

Because they're wild-caught, new puffers often carry internal worms. Quarantine them for at least four weeks and watch the belly. A puffer that eats well but stays thin or sunken usually needs a dewormer. Use one made for fish in the quarantine tank and follow the label dose.

Treat it as a species tank. Puffers bite fins, so bettas, guppies, angelfish, and gouramis are out. Cherry shrimp and amano shrimp get eaten. Fast fish like danios can outrun them but still lose fin tips. If you want something else in there, a group of six otocinclus in a mature, planted 20 long or larger usually works, since they stay on leaves and glass and have no long fins to bite. Keep a spare tank ready in case a puffer starts nipping them.