We recently lost 3 fish. Thought it was due to fin rot but having tested the water it turns out it was ammonia burn due to fish sitter upending food container into the tank (as far as I can see) . So.... is there any home test I can do short of spending out on a testing kit which are scarily expensive. I've spent about £20 on it recently in the way of new filters, fin rot treatment and ammonia treatment. And eventually I shall have to replace poor dead fishies when conditions are right.