I have a well established 240 litre juwel Rio fish Tank.
Up to yesterday i had fish in this tank that i have had for nearly 4 years (Bala Shark, 3 x Clown Loach) but all of a sudden they all started dying.
In the last 48 hours i have lost The Shark, all the Loaches, a Cory Dora Sterbae, and...