Algae eaters compared: shrimp, snails, and fish that work

Pick an algae eater by the algae you already have, not by the species that looked busiest at the store. Nerite snails clear diatoms and green spot. Amano shrimp work through soft hair and thread algae. Siamese algae eaters are the common option that will actually graze black beard algae.

Buy the wrong one and you add bioload to a tank with the same green glass.

Match the species to the algae you have

Adult sizes below are the figures published in standard species references. Minimum tank sizes reflect swimming room and territory rather than filtration capacity.

How each one behaves once it settles in

Nerites work glass and hardscape hard, and they lay hard white eggs on driftwood that will not hatch in freshwater. If the egg specks bother you, keep one instead of four. Full detail sits in our nerite snail care guide.

Video: Cichlid Bros

Amano shrimp are the strongest soft-algae grazers in the hobby, and they stop grazing the moment you overfeed. Cut back on pellets for a week and they go back to the algae. Our amano shrimp care guide covers molting and the copper problem.

Siamese algae eaters graze hardest as juveniles and slow down past 10 cm. Buy them young, keep three or more, and expect them to lose interest in black beard algae once they learn where the prepared food lands.

Tank size sets your shortlist before anything else

Under 10 gallons you have two real options: nerites and amano shrimp. A siamese algae eater in a nano tank is a fish you will rehome within a year, which is why it does not appear in our best nano tanks for aquascaping picks.

Otocinclus sit in between. They need established biofilm to graze, so they starve in setups younger than two months.

Stocking density decides the result more than species count does. One amano per 2 gallons is a sensible starting point, and going heavier mostly gets you shrimp competing for the same patch of hair algae.

What none of them fix

Algae eaters graze what has already grown. They do not shorten your photoperiod, drop your nitrate, or steady a CO2 swing.

If your tank grows algae faster than a cleanup crew can eat it, the crew is not the lever you are looking for. Cut the light duration first, then restock.