My fish!! why oh why!!

[cl78]

Hi All,

Newbie to the forum here, i have been battling for the last couple of weeks to understand what's going on in my tank.......my fish are dying!

Brief overview - 180L Rio tank with external filter, skimmer, 2 koralia 3 powerheads, water changes of 10% every 7-10days using self mixed RO.
Tank contains LR and has been up and running for a year, 10 corals - mainly leathers and mushrooms which are flourishing. Clean up crew including 2 shrimp and a seaurchin all doing fine.

Fish - i have lost a clown, a humbug damsel, atlantic tang, sgt.major damsel, royal gamma over the last few weeks leaving me with a sgt major damsel, purple firefish, normal firefish. There is no sign of any illness, all remaining fish look healthy (having been staring at the them for ages!!) and are eating well twice a day.

The only thing i can think of is it's the damsel that's been causing all the trouble?

Thanks in advance for any suggestions.

Craig

Tank Parameters - salinity 1.024
temp 24C
ammonia - nil
nitrite - nil
ph - 8.1
nitrate - 2.5

[greech]

Any type of metal or other foreign contaminant accidently make its way into the tank? How long between losses? It could be the damsel but if it were that aggressive I would think you would have seen some evidence with that many losses.

8 fish in a 45-50 gallon tank is a overstocked IMO, especially when one of them was a tang. Now that I think about it 3 damsels combined with that many fish in a tank that size might cause some aggression issues. Have you seen any torn fins, etc?

[Cerianthus]

Inverts (Corals) shouldve/wouldve reacted to heavy metal before fish but doesnt hurt to check when and if possible.

Since youve been staring these fish for ages, Any new additions recently?
It only take one new addition to cause nightmare!!!
Sometimes just drop of water from other tank.

Sgt Major is not that aggressive. I find striped damsel to be more aggressive.

With an assumptions that no visible symptoms noticed,
Skimmer working well?
Any carbon filtration?
Any new additives used?
Massive slimes produced by Leather? Funky Smell? Look at the bottom of substrate from underneath the tank. Any massive Black Spots/Patches?
I doubt H2S2 with good circulation unless massive release at night time.

Pics of tank/system?

[dolfans1]

Over what period of time have you lost the fish (i.e. in a day, a week, a month)? If it hasn't happened all at once, I think maybe you have an unknown hitchhiker in your tank like a mantis shrimp.

[Fishfriend1]

Did you see any parasites in the tank? Any Hitchhikers? New fish can carry invisible parasites or disease. Also maybe the tank was just overloaded and couldn't handle that may fish. Are they breathing heavy.

[cl78]

Thanks very much for your responses.....let see if i can answer those questions....

I can't think of any contaminant getting into the tank, nothing springs to mind. The last new additions i had to the tank were the 2 sgt major damsels a couple of weeks before christmas - they were bought from a different LFS than i normally purchase my fish from. The losses started on the 23/12 and have gone through to 02/01 so 10days.
Skimmer is working well it was stripped down and cleaned not long ago its a deltec mce300. i have carbon in the external aswell as phosphate remover. I'm currently not adding any additives to the tank - should i be?

there have been some slimes produced but i wouldnt call them massive but then i'm not sure what would count as massive?

Hitchhikers - i've not spotted anything but then that doesnt necessarily mean there isnt?

Remaining fish are all looking fine and eating and swimming normally 4 days now since the last loss.

I have linked to some pics of my tank.

Thanks again for your help

Craig

http://i867.photobucket.com/albums/ab232/luptonc/20100106_0629.jpg
http://i867.photobucket.com/albums/ab232/luptonc/20100106_0628.jpg
http://i867.photobucket.com/albums/ab232/luptonc/20100106_0627.jpg

[Cerianthus]

If rest of fish are Okay and water in acceptable range, I would just monitor for a while before adding new!

Cant say for sure whether it was due to new or not but Q/T new for few weeks should assist in prevention down the road.

Nice looking leather, colt and other corals.

As far as additives for corals, are you using any? Iodine, strontium, molypdenum, magnesium, etc, etc. For few corals you may not need but look into coral additives.

Hope tanks settles w/o further mishaps!