The subject sums it up really, I've gone from having 6 cherry barbs, 4 platys and a danio to 3 cherry barbs, 3 platys and the danio and it looks like another cherry barb is now starting to suffer.
The only thing I can think that I did wrong is I forgot to add Prime to one of the buckets before starting to add the water into the tank. I added about a quarter of the bucket before I realised my mistake, then I added the Prime. Is that enough to hurt the good bacteria in the tank?
I had an ammonia spike previously after losing a platy fry that we somehow lost; eventually I managed to remove the remains after frantically cleaning the gravel for a few days.
Other than water changes what options do I have? The dodgy water change was done last Sunday, if the cycle has been affected what can I do to halt the damage to my fish?
Re: Recurring 0.25 ammonia help needed please...
If you're using the API liquid tests, their ammonia test can show a false 0.25. Check against your tap water to see if that's the case. As for dealing with spikes, water changes daily and using a double dose of Prime in the new water will help protect your fish from the effects of both ammonia and nitrite.
There's a full article here on what to do in the event of ammonia and/or nitrite spikes: