Otocinclus care: why they starve in new tanks
Otocinclus do not usually die of disease. They die of an empty tank — quietly, over three weeks, while the keeper assumes the algae is enough.
Otocinclus are wild-caught in enormous numbers and arrive at the shop already thin. Their gut is short and they graze almost continuously; a tank with no biofilm and no algae has nothing for them, and they will not reliably switch to wafers.
The three conditions
- A mature tank. Three months minimum, with wood, plants and visible film on the glass.
- A group. Three or more; a single otocinclus hides and stops eating.
- Zero ammonia, zero nitrite. They are more sensitive than the fish they share a tank with.
Feeding when the algae runs out
Blanched zucchini, spinach or cucumber weighed down overnight; Repashy or a dedicated gel food; and a piece of driftwood they can graze. Rotate so nothing rots, and remove uneaten vegetable matter after 24 hours — in a small tank it decays into exactly the ammonia they cannot tolerate.
A healthy otocinclus has a rounded, slightly sunken-but-full belly. A flat or hollow one is already in trouble. If you see it on day three, the tank is not ready — return the fish rather than watch it decline.
Frequently asked
Will otocinclus eat all my algae?
Can otocinclus live in a 5-gallon tank?
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