Rummy-Nose Tetra Feeding: Wild Diet, Staples, and How Often to Feed

The rummy-nose tetra (Petitella bleheri, formerly Hemigrammus bleheri) eats almost anything put in front of it, as long as it fits. An adult reaches only about 2 inches (5 cm), it has a small mouth, and the whole job of feeding one comes down to three things: small food, plenty of variety, and portions the school can finish.

Feeding Schedule by Life Stage

Rummy-nose fry are notoriously hard to feed, juveniles get several small meals, and adults need food at least once a day.

The eggs hatch in 24 to 36 hours and the fry swim free 3 to 4 days later. Both are sensitive to light early on, so the rearing tank stays dim. The fry are so tiny that feeding them is the hard part of breeding this fish, and a mature 10-gallon breeding tank with plenty of mulm gives them microfauna to pick at between meals. Moving them onto live baby brine shrimp as early as they can manage it improves both growth and survival. Adult rummy-noses eat their own eggs given the chance, so breeders move the adults out once eggs or fry appear.

For adults, judge the portion by watching the fish eat. If pellets are still sinking untouched once the school loses interest, cut the next pinch down, because leftovers rot into ammonia that the nitrogen cycle in a mature tank then has to process. Watching also shows whether the rummy-noses are eating at all.

What Rummy-Noses Eat, in the Wild and in the Tank

In the middle Rio Negro basin of Brazil, the stomach contents of 177 wild fish show an omnivore, and most of what it ate was produced inside the water itself rather than dropping in from the forest above. The menu shifted with the river. During the flood, microcrustaceans made up a larger share. In the dry season the fish leaned more on filamentous algae, chironomid (midge) larvae and fragments of plants.

That mix of tiny animal prey and plant material is the template for the tank: a dried staple that covers the basics, with small crustaceans and insect larvae offered alongside it.

Base the daily diet on a quality dried food: flake, granules or a slow-sinking micro-pellet. A varied diet is what brings out the best color and keeps any one nutrient from running short, so rotate between two or three dried foods instead of relying on one tub. Getting the fish to eat is seldom the problem: rummy-noses chase almost any community food across the tank, eagerly enough that at least one fish store uses them to try out new foods.

Small live and frozen foods round out the diet and come closest to the microcrustaceans and midge larvae of the wild menu. Good choices include baby brine shrimp, brine shrimp, daphnia and mosquito larvae. Krill and salmon-based foods are also fed for color.

Daphnia, one of the closest live matches to the wild diet, comes with a catch: it and cyclops are common intermediate hosts of Camallanus, a parasitic worm that infects the fish that eat them.

An opened container of dried food kept at room temperature is thrown out 2 months after opening, and one kept in the freezer after 6 months. Frozen brine shrimp, bloodworm and similar foods last a year, and once thawed they never go back in the freezer.

Foods to Avoid

• Anything too big for the mouth. Flake and pellets sized for bigger fish are hard for a rummy-nose to take, and whatever it cannot eat rots on the substrate.
• Live tubifex worms. Tubificid worms are the host of the parasite behind whirling disease, and keeping fish away from them is how that disease is prevented.
• Pond-caught cyclops and daphnia. Wild-collected crustaceans are the same Camallanus hosts as cultured ones.

Why Rummy-Noses Stop Eating

1. Boisterous or bigger tankmates. This is a gentle fish that loses out at feeding time to rowdy or much larger company, which can take most of a meal before it gets a share. Companions of similar size and calm temperament, picked with the compatibility checks for a shared tank, keep the food going to the fish it was meant for.
2. Stress from the tank. Bad water and low temperatures both stress a rummy-nose, and in alkaline water rising nitrate can cause a marked loss of color as the first sign.
3. Internal parasites. Spironucleus, an intestinal flagellate, causes weight loss and loss of appetite, and it kills fry and juveniles.

When to Worry

A well-fed rummy-nose school is busy and tight, with bright red heads and slightly rounded bellies. Mature females are noticeably rounder in the body than males, so a plump female is not a sign of overfeeding. The signs that need action:

• The whole school pale. Food alone will not keep the red nose bright, and a nose that fades on every fish at once points to the tank, and a school that has gone pale needs a water test and a look at the heater before anyone changes the menu. Fish that have just arrived or were just chased with a net can look washed out too, so give them half an hour, or another day, to color up before reading anything into it.
• A nose that stays pale after the water tests clean. Disease and bullying fade the red as well, and the rummy-nose tetra health guide sorts out which one it is.
• One fish thinning while the rest eat. That pattern points to the fish, not the tank, and an internal parasite needs a diagnosis before any medication goes in.

When You Go Away

Someone has to feed the fish while you are gone, either a person or an automatic feeder, and both can put in too much for a school this small.

For a sitter, measure out every meal before you go, for example into a labeled pill organizer with one compartment per feeding, so no extra food goes in. Show them once how it works, and leave your number.

For an automatic feeder, set it up and test it for several days before the trip, using a food it dispenses well, and check that it is not jamming or overfeeding.

A rummy-nose fed small, varied food in portions it can finish has almost everything the wild Rio Negro gave it.

Sources & Further Reading