Who Gives A Fish Forums

I've got a 20 gallon planted tank with a school of 6 neon tetras and a betta. Thinking about adding some Otocinclus to help with algae. How many would be safe without overloading the tank? Water params are stable, 0 ammonia, 0 nitrite, 10 nitrate.

Otocinclus are social, so you'll want at least 3 to keep them comfortable. In a 20 gallon, 3-4 would be fine with your current stock. Just watch the bioload, they're small but still add to it. What's your filtration like?

Saltie wrote: ↑Thu Jun 19, 2025 4:21 am Otocinclus are social, so you'll want at least 3 to keep them comfortable. In a 20 gallon, 3-4 would be fine with your current stock. Just watch the bioload, they're small but still add to it. What's your filtration like?

I agree with Saltie. Also, make sure you've got plenty of biofilm or algae for them to graze on. They can be picky eaters if the tank's too clean.

I'd start with 3. They're tiny but can be sensitive to changes. If they settle in well, you could add another later. Have you checked your pH? Otos prefer it stable around 6.5-7.5.

Yo, 3-4 sounds chill. Just don't go overboard. They're gonna need some hiding spots too, like driftwood or dense plants. My otos love hanging out on my spiderwood.

Thanks for the advice, everyone. I'll start with 3 and see how they do. My pH is around 7.0, and I've got a sponge filter plus a small HOB. Plenty of java moss and driftwood for biofilm.

Good call starting small. I made the mistake of adding 6 to my 20 gallon once, and it was sketchy for a bit. They're cute but can be finicky.

Just wanna say, otos are the best. Mine are always busy cleaning the glass. Hope yours settle in quick!

I've heard they do better in groups of 5+, but I'm not sure if a 20 gallon can handle that with your other fish. Maybe stick with 3 for now.

3 sounds safe. They're small but add up. Keep an eye on your nitrates after adding them.