Marine fish dying and unsure why

[Musteve]

Hi,

I am really having problems with my fish as I have lost 4 in the space of four weeks and I have no idea why!! I have a 350 litre tank, with a sump, phosphate and nitrate reactors, protein skimmer, uv steriliser and polypad. I had the following fish:

Copperband butterfly fish
Lipstick tang
Regal tang
2 x clowns
Emporer angelfish
Yellow tang
Royal gramma
Fire fish

Over the last 4 weeks I have lost the yellow tang, lipstick tang, butterfly and gutted but emporer. My water quality is virtually perfect and I top up regularly with RO water. Also starfish has just died. The fish look healthy and I'm at my teather at the mo. Any help or guidance would be great. The tank has been running since November and before that I had the same issues when running for three months. Thought I had sorted the issue but clearly not!!

 

[Musteve]

My water quality is as follows:

Salinity 0.124
Nitrates 5
Nitrite 0
Ammonia 0
Phosphate 0,3
Magnesium 1320
Kh 12.5
Calcium 420

 

[lmforbis]

I can't rule out a disease but your tank is really way to small for that many fish to begin with especially big fish. The lipstick, Regal, copper band and emperor need a much much larger tank. Most will get to over a foot in length with the lipstick getting 1.5 feet. Copper band butterflies are difficult to keep under the best circumstances. If I am doing my math correctly, 350 L is on the order of a 75 gallon tank. Without the 4 fish I mentioned you would have been more appropriately stocked and the adult size and behavior patterns of the fish would be perfect in your tank.
When large fish like tangs or large angels are kept in a too small tank they become very stressed. Stressed fish are susceptible to disease and will get very aggressive. Tangs especially need room to swim for their mental well being even if they are very small. I have a regal that is less than an inch long and she swims the whole length of my 6 foot long tank.
Pay attention to the adult size of your fish and keep the stocking appropriate for you tank size. Research the behavior habits of your fish before you purchase them. I would also recommend quarantining you fish for at least 30 days before adding to your tank so you don't introduce a disease to the tank, infecting the rest of the fish.

 

[beth]

Also, you have 3 tangs in a 90 gal tank. The starting point for tank size for tangs is normally 125gal. Very likely aggression among the tangs.

 

[jay0705]

Agreed. Tangs need more room, I have 2 of the 3 you mentioned. No issues at all, but a much larger tank

 

[Iron_brigade]

Are you saying that even a 2x2 -3x3 size yellow tang is to small for a 75 gal? Even if its the only tang in about 5 small fish total?

 

[Kristin1234]

Are you saying that even a 2x2 -3x3 size yellow tang is to small for a 75 gal? Even if its the only tang in about 5 small fish total?

I would say yes. 75 is too small for any tang.

 

[bang guy]

Are you saying that even a 2x2 -3x3 size yellow tang is to small for a 75 gal? Even if its the only tang in about 5 small fish total?

It has nothing to do with the size of the Yellow Tang. It's the swimming habits of this fish. They require swimming room. Four feet just doesn't cut it. Six feet is the minimum in my opinion for long term health but it's definitely your choice. Best of luck.