No offence if i am taking your method of fishkeeping wrongly but is the tank cycled with active filter media?

My first fishkeeping experience was when i was bought a fish bowl with a black moor and i didnt have a clue.

I carried out some reseach and found that there had a to be an active community of beneficial bacteria within the tank to provide stability for the water conditions, also preventing fluctuations of harmful chemicals to the fish.

If this is carried out then take a standard method and keep up the daily water changes and make sure that the fish have some oxygen to breathe, either some coldwater plants like pond weed or a little air pump with air stone.

hope this helps...

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Dom