Lost a lot of fish lately

Ive had a bad run in the last week or two with my fish.
My two desert gobies died after having them for a few weeks with no problems. I bought two julii corys and two pygmy corys and lost both my pygmys after a few days while the juliis are still fine. My longfin albino bn died about a month ago for unknown reasons and now I've lost my big breeding male bn all of a sudden while my female has also seen better days but she's still hanging in there for now.

I did some tests on my water a few days ago and found that the ph was a little lower than usual which isn't too bad. The ammonia was fine, nitrites were up a little so I did a 10% water change, and nitrates were also at a reasonable level. The next day the nitrites were back to 0 but I lost my male the next day.

After talking with a friend of mine today about whats been happening, he's working on a theory that I may have traces of copper or something in my tank because all the fish that are dieing are catfish types and lack scales. The rest of the fish are perfectly healthy. Rummynose tetras, black phantoms, rasboras. My peppermint bristlenose doesn't seem to be affected (yet. fingers crossed)

So this afternoon I did another 10% water change and dosed with some prime. I'm taking a water sample to the shop tomorrow to get some more thorough tests that I can't do at home to try and find what the problem is.

Sorry for your losses.
I don't think its copper as i've dosed catfish with copper meds before without problems. I think i'd take a lot of copper to cause problems.

Another similarity is that all the fish were bottom dwellers (gobies aren't catfish). People only having problems with bottom dwellers is another issue that comes up often and is related to the substrate not being as clean as it could be. The substrate could have either gone anaerobic or has a build up of bacteria. What type of substrate do you have and how often & how do you clean it?

Another issue could be the addition of fish without quarantine. Its easy to introduce diseases to your tank which can cause problems if you don't quarantine new additions.

Could be with the rain lately the council has stepped up the water treatment. Goodness knows what they are putting in. You might have to dose with prime in the tank daily until things settle down.

well i took the a water sample to get tested today and my water is reeeaaallly hard. A hardness test kit is something I don't have. I've gotta get something to soften the water.

My substrate is a very fine gravel and is pretty clean. There's only about a centimeter covering the bottom of the tank and when I was doing water changes I was sifting through it to see if it needed cleaning and there was almost nothing coming out of it.

I did a water changed yesterday and dosed up on prime. My female bn is still hanging in there like a trooper so fingers crossed she pulls through all this.

maybe add some oak leaves or almond leaves ( dry ones ) usually you can get these at the LFS. cheers jk :thumbup:

oh dear, water is so important, can you use rain water?