3 tiger barbs and my rainbow shark . Used my Python, sucked out about 75% of the water (as usuall) and while the new water was going in those fish started acting funny and within 3-4 minutes, tank is full and fish are dead. I treat the water little by little as it is refilling via the Python, all of these steps have been the way I have done water changes daily for a longe time now.
Any ideas.
Any ideas.