Lost 2 fish this week, water testing fine.

[Endler32]

Lost a cory yesterday, some of my other fish were acting oddly, hanging out near the surface, tested water, ammonia 0, nitrite 0 and nitrate 40 (a bit high), did a 50% water change and all the fish seemed happy, got up this morning to a dead gourami . One of my female Beta is near the top but she does this from time to time when she's egg bound, my tetras seem happy and my Pleco are perfect ( more babies in the cave ). So it's a bit of a mystery, I have gone ages with out loosing any fish and in the past week I have lost 3 including my male beta in another tank.

Looks like I'm going to loose the female fighter, her face looks pale and eyes look cloudy. Tested water again and nitrate still high even after water change.

Have you tested your tap water nitrAte? Although tbh I wouldn't suspect that it is the nitrAte causing problems. 40 is about as high as you'd want it to get but it shouldn't be causing problems like this. Are these similar to deaths that you've had before?

Tap nitrate is testing a lot lower than my tank, have done another water change. Just lost the female beta , her face went white and her eyes clouded over, took her out and she died not long after. The gourami had a hole in its side when I found him but probably from the other fish trying to eat him? Never had anything like this, the cory was acting oddly before he died, came out of his hiding spot and was gasping, he died shortly after, what ever it is it seems to be taking them quickly . I have a new tank but am waiting for a heater so I can set it up as a hospital tank if any others get poorly but I suspect there won't be enough time to treat them.

I have checked everything in my tank, last week I bought some neons but they all seem healthy, also bought a new plant which my Pleco have shredded, I have taken this out.

I hope I don't loose anymore as I have a fully stocked tank, I don't want to loose them all.

Just remembered, last week I replaced one of the hoses on my external filter, also rinsed my filter sponges ( in tank water ), I can't think of anything else that I have done that could have caused a problem.

If it was only last week then you'd expect to see some ammonia and/or nitrIte showing up if the filter had been knocked back a bit.

The hole in the gourami may have been an ulcer. Lots of pictures here to see if that's it (not while you're eating!)

Cloudy eyes can be a sign of a few things. When her face went white, was there any fungus or extra mucus or was it just a loss of pigment?

How often do you check your fish? If this is happening very suddenly then it could be some kind of poisoning but if it's happening gradually then it's probably pathogenic.

Have you tested the pH?

I check them a lot ( watch the fish more than the tv ) , just looked like pigment change in her face, the rest of her body was perfect, she was fine last night, happily swimming around, found her like this this morning along with the dead gourami, hard to tell with the gourami as it must have died in the night and got half eaten by the tetras. Ph is 7.6 which is where it always is. I'm trying to think if anything could have gotten into the tank but I can't think of anything, havnt used any cleaning products this week ( kids are home so there's no point ). I guess all I can do is daily water changes? I have done 2 big water changes so hopefully if there is anything in the water it will clear off.

Still loosing fish , lost a tetra yesterday and one of my favourite female fighters this morning. Have done another large water change, not sure what else to do. It has taken me months to build up my female fighters ( gradually adding them ), now I'm looking at starting again.