Help!

Hiya,

I posted a while back regarding poor readings in my tank. I managed to get the nitrite and nitrate levels down and they are all reading perfectly with no issues and no loss of fish!

Unfortunately in the past week we have lost 4 fish out of 15 and I can’t figure out why.

All levels are reading fine including the test kit in the photo and a separate ammonia testing kit.

We do a half water change every week and feed them every 3 days.

Please help!

Thanks

BASIC FIRST AID FOR FISH
Test the water for ammonia, nitrite, nitrate and pH. Post the results in numbers here. (You have done this part so that is good).

Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.

Do a 75% water change and gravel clean the substrate every day for a week or until the problem is identified. The water changes and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.

Post clear pictures and video of the fish so we can check them for diseases.
You can upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally (landscape mode) so the footage fills the entire screen and you don't get black bars on each side.

---------------------

If the filter is established you can feed the fish once or twice a day.