I set up a marine tank some 18 months ago and have in that time only lost 2 fish. However, in the past week my tank has been decimated and I have lost all bar 4 of my fish. To date I have lost two cardinal angels, one fox face (second one does not look that well), 3 damsels, 1 sail fin tang, two blennies. 1 sea pen, 3 clowns two of which were a matched pair for breeding they were also the first marine fish I owned, 1 empror angelfish which had just started to transform into the adult it would become. To say I am gutted would be an understatement. I check the water quality regularly and it is allways within the permissible range. I have left 1 cow fish, 1 fox face, 1 picaso and 1 damsel. My enenome and hermit crab seem unaffected by what is happening. I started a course of Kent RXP and am continuing along this line. On inspecting the fish I can see no obvious signs for their death so am at a loss. No new fish have been introduced to the tank for the past 6 to 8 weeks

The tank is a vision 350 with an external filter plus the internal filter and heater. I have a prism skimmer as well which runs 24*7.

I am unwilling to purchase more fish and put them in the tank until I know for sure I will not just be consigning them to death.

Has anyone got any ideas at all, all help / ideas gratefully accepted. You can mail me at mick@cabcomputing.freeserve.co.uk

You didnt say how big the tank is or the volume of water.The volume has little to do with tank size.You start of with the dimensions to give you the volume empty. Every piece of rock.sand etc displaces water.If the tank is over crowded infection spreads like wild fire.Since your water quality was fine its probably infection caused it.The fish become weakened and Die.
Id make sure every thing is clear before replacing
Peter

Hi,

I am going through a similar problem...but I know mine is white spot disease (ich). I noticed it on my cowfish immediatly...however only noticed it on my coral beauty because it was scrathing itself - coudnt really see the spots until it was covered.

Has the behaviour of you fish changed at all? feeding? color? it could possibly be a inernal parasite...in which case you would have to check or get it checked under the microscope...you can either investigate the fish droppingd...or do a disection when the fish dies - to find ut what it is.

Janina