Yesterday my partner did a 75% water change. Tank is 90L and fully cycled. Fish - Molly (the one that's died), 5 corys, 6 harlequins, 5 platys. Also have 2 assasin snails. Live plants in tank. Nothing new added recently. During the water change my partner did disturb the sand substrate and cut back an overgrown plant. Cleaned the sides.
I found the molly dead in the tank and the fish all "breathing" at the surface, even the harlequins. Corys shooting up to the surface more than normal. Removed dead fish from tank and checked ammonia levels. 1 minute after mixing the test (have the API Master kit) it was yellow saying no ammonia. About 5 minutes later it's still yellow, not even slightly green. My partner looks after the fish, I don't have a lot to do with them normally. I'm going on a night shift at 9pm tonight (british time) and my partner won't be in until about 10pm.
Edit: My partner recently got a new filter which is much stronger about 2.5 months ago. However, both the new and old filter are on together and will be for at least another month.
The molly has been sickly before. It once had an infection which we treated with antibiotics successfully. It has also been attacking the plants recently and generally showing signs of frustration. My partner was advised by someone (maybe this forum I think) that our molly wasn't attacking or eating the plants but being frustated.
Edit 2: Last night the molly was really splashing about and I thought one of his eyes looked darker than normal. This morning when I turned the light on and fed them the fish weren't as excited when I put the light on and not as interested in the food. We assumed it was because they were fed later than normal the night before, and slightly earlier this morning.
Edit 3: The 2 larger platys seem to be really struggling. After getting advice elsewhere on the internet from reading threads of people with similar problems (but they got help) I've taken about 4 litres of water from the tank and moved the filter so that its splashing to get as much oxygen in the water as possible. The general consensus is that if ammonia is ok chances are its oxygen.
Edit 4: All platys seem to be trying to be near the surface. The biggest red platy however keeps drifting away, face pointing down as if its bottom is floating yet lying down on the floor, before eventually going back to the surface. The other large platy (orange and white) keeps twitching, as if its having a fit, before lying on the floor briefly and then getting back to the surface again.
I found the molly dead in the tank and the fish all "breathing" at the surface, even the harlequins. Corys shooting up to the surface more than normal. Removed dead fish from tank and checked ammonia levels. 1 minute after mixing the test (have the API Master kit) it was yellow saying no ammonia. About 5 minutes later it's still yellow, not even slightly green. My partner looks after the fish, I don't have a lot to do with them normally. I'm going on a night shift at 9pm tonight (british time) and my partner won't be in until about 10pm.
Edit: My partner recently got a new filter which is much stronger about 2.5 months ago. However, both the new and old filter are on together and will be for at least another month.
The molly has been sickly before. It once had an infection which we treated with antibiotics successfully. It has also been attacking the plants recently and generally showing signs of frustration. My partner was advised by someone (maybe this forum I think) that our molly wasn't attacking or eating the plants but being frustated.
Edit 2: Last night the molly was really splashing about and I thought one of his eyes looked darker than normal. This morning when I turned the light on and fed them the fish weren't as excited when I put the light on and not as interested in the food. We assumed it was because they were fed later than normal the night before, and slightly earlier this morning.
Edit 3: The 2 larger platys seem to be really struggling. After getting advice elsewhere on the internet from reading threads of people with similar problems (but they got help) I've taken about 4 litres of water from the tank and moved the filter so that its splashing to get as much oxygen in the water as possible. The general consensus is that if ammonia is ok chances are its oxygen.
Edit 4: All platys seem to be trying to be near the surface. The biggest red platy however keeps drifting away, face pointing down as if its bottom is floating yet lying down on the floor, before eventually going back to the surface. The other large platy (orange and white) keeps twitching, as if its having a fit, before lying on the floor briefly and then getting back to the surface again.
