Amanos starving out corys?
I was curious if anyone had some experience with amanos outcompeting their corys..
For context I've kept corys for about 4 years now. I had a batch of fish I carefully quarantined up for a month then added to an established tank (2+ years old) about 6-8 months ago. I've been gradually loosing corys one by one & am at about half of what I started with. They just seem to waste away. I've tried treating with Expel-P before (and am currently starting a longer course just in case its a parasite with a long life cycle), but it doesn't seem to help much.
Tank is 22 G, fully planted. Mix of venezuelan, peppered, and panda corys. Some are quite chonky, others aren't (and to me seem to have grown very slowly)... it seems some just aren't very boisterous feeders. A few weeks ago one of my old ammonia tests was giving me false-positives so I cut feeding for a week to "get it under control" - which only seemed to hasten the #s I lost.
I have about 3 amanos in that tank and I've seen them steal pellets. I was feeding some bigger ones, so I was adding about 4-5 pellets in the tank every other day. In light of that I started feeding more often & "tinier food" to see if I can get my weaker feeders to bulk up. I'm also thinking of getting a blackworm culture going.. just to get these guys nice and plump. Presently I feed them freeze-dried tubifex, hikari nano-bites, bug bites for bottom feeders, crab cuisine, the occasional frozen brine shrimp/blood worms.
For context.. tank has a pH of 7.6, and last I measured ammonia of 0, nitrite of 0, nitrates around 20 ppm. I used to change the tank water maybe every month or so (plants do a good job keeping everything clean) but have shifted to weekly water changes just to rule out issues. Tank flow dynamics are very good in that tank so I don't have any mulm build-up. Tank mates include 3 free-loading amanos, 4 CPDs, and neocaridina shrimp.