Feeding killifish: live food, frozen food and why they refuse flakes
Many beginners buy a pair of killifish, pour in shop flakes and find a week later that the food sinks untouched. This is not fussiness for its own sake: the killifish is a predator of small live prey, triggered by movement. Published breeding protocols confirm it. The reference protocol by Matej Polačik, Radim Blažek and Martin Reichard, published in 2016 in Nature Protocols for laboratory breeding of the turquoise killifish Nothobranchius furzeri, describes a diet based on brine shrimp nauplii for juveniles and then bloodworms for adults, fed several times a day (study on Google Scholar). The killifish profile covers its other husbandry requirements.
The base: live or frozen
In a home aquarium, a realistic menu rests on three pillars. Frozen bloodworms are the staple, readily accepted by most species. Frozen or decapsulated adult brine shrimp add variety and restart the appetite after a refusal. Daphnia, frozen or live, act as roughage and limit digestive problems. Always rinse thawed frozen food before feeding: the thaw liquid loads the water with nitrates without feeding anyone.
Live food remains the best trigger
For a killifish that refuses everything, nothing replaces movement. Hatching brine shrimp at home almost always restarts the appetite, including in adults — the process, very simple, is covered in our guide to hatching brine shrimp at home. Microworms and grindal worms are just as easy to culture and give you a daily live source without depending on a shop.
Is it worth persisting with pellets?
Yes, but do not rely on them. Some individuals accept carnivore micro-pellets provided they sink slowly and are offered right after live food, while the fish is already in hunting mode. That is a holiday convenience, not a staple diet. Never count on floating flakes: most killifish feed in mid-water and ignore whatever stays on the surface.
Rhythm and quantity
Two small meals a day beat one large one, with a weekly fast for adult annual species, which put on weight quickly. The "all eaten within two minutes" rule remains the best visual guide. In fry, by contrast, frequency dominates: three to four daily feeds, along the lines described in our article on first meals for fry, shape growth in the first weeks.
Watch what feeding reveals
A killifish that suddenly stops eating after happily taking live food is almost always signalling something other than a whim: temperature too low, degraded water quality, or the natural end of the cycle in short-lived annual species. Our other feeding benchmarks are grouped in the aquarium fish food section.
Frequently asked questions
Can a killifish live on dry food alone?
It is not advisable. Even individuals that accept pellets do better with frozen or live prey making up the majority of the diet.
How long can a killifish go without food during holidays?
A healthy adult copes with a few days, but beyond a long weekend it is better to arrange for someone to feed frozen food than to use a feeder block.
Are frozen bloodworms risky?
Bought as commercial blister packs and kept frozen without a break in the cold chain, they are safe. Avoid live bloodworms collected from the wild, whose origin is uncontrolled.
This guide is part of Planète Pets’s Fishkeeping universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.