Hi everyone I’m hoping you can help me! I came back from Australia 3 weeks ago my mum had been looking after my house and my fish, I did a water change before I left ( I was there for 2 weeks ) when I came back I noticed one of my platys didn’t look well and wasn’t eating he has clamped fins and constantly hiding and hasn’t eaten for ages now. I immediately did a water change and went to the pet store to ask for advice they told me my ammonia was a bit high, I’ve been doing a lot of water changes adding aquarium salt and bought more live plants. I went back a few days later and the ammonia was 0 but my nitrate was high they said all I can do is keep doing water changes. I asked about any disease’s and showed them pictures and they said it’s definitely poor water quality. Now my black moor has become poorly and doing the same as the Platy the rest of my fish are fine which include( another Platy, minnows, shrimp, loach,) my black moor is still eating but he’s just laying on the bottom of the tank he hasn’t done that in the whole 2 year I’ve had him. I’ve looked for the obvious looking diseases but can’t see anything I will attach pictures. Please if anyone knows what this can be and how to treat them please comment, thank you

If your nitrate is high that will be the reason he black moor is lying on the bottom. Fancy goldfish are well-known to suffer effects with their buoyancy from high nitrate. Concentrate on getting that down and he will hopefully recover.

I agree too. The sooner you can get this addressed, the less likelihood there is of the others succumbing one after the other to the effects of the high nitrate.

How often and what quantity of water changes (i.e. percentage of total volume) are you currently doing?