Just checking - you're using water conditioner now, right? Been reading the thread and you've had some great advice but I didn't se this mentioned again.
For water conditioner, don't just get the cheapest. Get one that removes chlorine, chloramine and heavy metals, and ideally on that states it locks ammonia into a safer form (you get ammonia from breaking down chloramine as well as from fish).
By a viking fighter did you mean a siamese fighter AKA betta splendens? These are not generally recommended for community tanks, especially not ones with cichlids like angel fish, fin-nippers like danios and aggressiv fish like sharks.