My chili rasboras FINNALLY got their natural color but then I got a blue green algae so I put a blanket over the tank for 3 days but it only killed half of it. I'm going to buy a solution tommarrow to kill it but i just wanted to know if the blue green algae would poison the otocinclus I that I recently added. Also one of the otocinclus has a huge belly and it is not eating and has not moved for 2 days I think it may be bloated but how do i cure it if it won't eat?
Do
NOT use any chemical product. These will harm fish.
BGA is not an algae it is a bacteria, cyanobacteria, and it is caused by organics in the presence of light. The "blackout" will not work long-term because without removing the excess organics the cyano will only return.
No fish will eat cyano, so the only way to get it under control is by reducing the organics. Organics naturally accumulate in any aquarium with fish that are fed. Not overstocking, not overfeeding, regular (once a week) partial water changes of 50-65% of the tank volume, keeping the filters rinsed, and vacuuming the substrate will all reduce organics. Plant additives (fertilizers) can also contribute. Having so-called plant substrates or soil will also contribute. I'm not saying all of these apply, but these are the relevant factors.
When you do the water change, remove (loosen) as much of the cyano as you can (use your fingers) so you can suction it out with the water. It may take a few weeks before it stops increasing between water changes, so don't expect it to disappear overnight.
Light can also be a significant factor. Too strong a tank light, or on for too long, can be issues.