Rungwa annual killifish

Where they come from

Rungwa annual killifish (Nothobranchius rungwaensis) come from seasonal pools in Tanzania. These are puddles that show up during the rains and then dry out completely. The fish grow fast, breed fast, and the eggs ride out the dry season buried in the mud.

That whole lifestyle explains why they act the way they do in our tanks: short lives, big appetites, and a serious urge to breed whenever conditions look good.

Setting up their tank

I treat these like a species tank project, not a community fish. A simple setup works best because you will be doing frequent water changes and you will want to find eggs easily.

• Tank size: 10-20 gallons is plenty for a trio or small group (1 male with 2-3 females). Bigger is easier to keep stable.
• Filtration: sponge filter or gentle air-driven filter. They do not love getting pushed around.
• Flow: low. If their fins are always clamped or they hide at the bottom, check your current.
• Cover: tight lid. Nothos can and will jump, especially during chasing.
• Lighting: moderate. Floating plants help them feel secure and keep them out in the open.

For decor, I go with a bare bottom or a thin layer of sand. Add some cover like Java moss, floating plants, and a few clumps of easy stems. The real key piece is a spawning container with peat or coconut fiber.

Water numbers do not need to be fancy, but stability matters. I have had the best luck in neutral to slightly hard water with a pH around the high 6s to mid 7s. Temperature in the low to mid 70s F keeps them active without cooking them. Warm water speeds them up, including aging.

What to feed them

They are little predators. You can get them onto quality pellets, but they really come alive on frozen and live foods. If you want color, fin shape, and breeding, this is where you spend your effort.

• Staples: frozen bloodworms, brine shrimp, daphnia, mysis (chopped if needed).
• Live foods that make a difference: blackworms, live brine shrimp, grindal worms, mosquito larvae (if you can source safely).
• Dry foods: small sinking carnivore pellets and high-protein flakes, used as backup or to round out the diet.

Feed small amounts 1-2 times a day. They will beg like puppies and act starving even when they are not. If you overdo it, the tank goes sour fast.

How they behave and who they get along with

Males are gorgeous and they know it. Expect displaying, chasing, and occasional fin damage if you keep more than one male in a small tank. I keep one male with a couple females and the whole tank settles down.

They are not "mean" in the cichlid sense, but they are pushy, fast, and food-focused. Anything small enough to fit in the mouth is on the menu, and slow fish will get stressed.

• Best option: species-only tank.
• If you insist on tankmates: think tough, quick fish that like similar water and can handle heavy feeding (still risky).
• Avoid: shrimp, small rasboras, guppy fry, long-finned fish, and anything you would be sad to lose.

Breeding tips

Breeding is half the fun with annual killifish, and honestly it is how you keep the line going since the adults do not stick around forever. They bury eggs in peat, and you can store those eggs like little time capsules.

• Conditioning: feed heavy with frozen/live for a week or two. You will see the male display more and females plump up.
• Spawning: keep the peat container in the tank full-time or rotate two containers so you can collect regularly.
• Collecting eggs: squeeze out the peat until it is damp, not dripping. Pick out obvious debris and store the peat in a labeled bag/container.
• Incubation: keep the peat slightly moist at room temp. Check occasionally for fungus and for eye-up (you will see tiny eyes in the egg).
• Hatching: re-wet the peat with cool, clean water in a small tub. Gentle aeration helps. Fry usually pop within hours to a day.

Fry are hungry right away. Newly hatched brine shrimp is the go-to, plus microworms or vinegar eels for the first days if you have them. Keep the fry water clean and shallow at first, then grow them out with lots of small water changes.

Common problems to watch for

Most issues with Nothobranchius come from three things: dirty water, too much aggression, or food going bad in the tank. They are tough in some ways, but they are not forgiving of neglect.

• Jumping: always use a tight lid, and block filter gaps.
• Fin damage: usually male-male conflict or constant chasing. Reduce males, add cover, or split the tank.
• Bloat/constipation: common with heavy frozen foods. Use smaller portions and mix in daphnia.
• Sudden losses: often tied to ammonia/nitrite spikes or old, dirty water. Test, change water, and keep feeding under control.
• Egg fungus: peat too wet, poor airflow in storage, or dirty peat. Keep it damp and check bags periodically.

One last real-world note: their lifespan is short even in great conditions. Do not take it personally if an older fish fades after several months. Focus on keeping the adults comfortable and getting a good batch of eggs so you always have the next generation ready.