Why did my Lemonpeel Angelfish die? And so suddenly? Now what?

[alink]

Hi Everyone,
I own a small 90 Litre (sorry I don't know the conversion to gallons) Salt Water Aquarium with about 7kgs of Live Rock, coral sand, which I've been cycling since early August 2009. I have not yet performed my first 'water change' as per my Local Aquarium's advice.

I've currently got a pair of mated reef Percular Clowns (first in), a Flame Angel and 6 x Domino Damsels.
I introduced the 6 x Dominos on Saturday and all went well with the introductions, apart from a little territorial behaviour from Flame Angel nipping at the new damsels who came near his domain.... all other fish good.
Yesterday (Monday) I found my Lemonpeel Angel lodged head first in one of the live rocks crevaces... I thought maybe he was stuck so I nudged him with a net and he swam swiftly to the back of the aquarium behind another rock and layed down on the sand. Within the next half hour he stopped moving altogether and died.

As I mentioned I'm still cycling the tank, the nitrate has not yet spiked completely and is currently measuring 20ppm (ammonia 0 nitrite 0)... was this the reason for Lemonpeel's death? Was he the most sensitive? (all other fish are behaving normally and eating well)
Or was he not impressed with the new introduction of little gangsters (dominos)? (Although they didn't seem to physically bother the Lemonpeel as he was the peaceful one, not like Flame) Perhaps it was the biological load increase (the addition of 6 fish at once) that caused Lemonpeel's death?

Anyway, I'm very upset at his death. I feel like I've failed at my aquarium hobby before I've even filled my tank with fish! If I could get some advice on what the possible cause of death was, I'd like to understand better and I'd be very thankful.

Regarding fish compatibility, I introduced my Dwarf Angelfish at the same time (thinking/hoping they'd both be in the tank for a long time) so now I can't add any more Dwarf Angelfish because the Flame will get aggressive towards the new inhabitant.... right?? Can I introduce another Dwarf Angel after a certain amount of time? After a year of keeping a healthy Aquarium perhaps?

(Out of interest, the only other livestock I wanted to add after my water change was a Sixline Wrasse, a Blue Tang and an Anemone. I did my research with compatibility, but never took into consideration early death of a fish in a pair)

Any advice from Marine keepers would be really appreciated.

Thanks

[StormySkiez]

Welcome alink to the site.

I'm sorry about your loss. I'm not a marine fish keeper. I do have some experience with fish keeping. Your tank size is aprox 23 us gallons.

It's very hard to know why your fish died Without obvious symptoms. Don't blame yourself for the fish dying. Fish are put through an extreme amount of stress being sent to the fish store to be put up for sale. The fish store didn't help any with their advice. IMO You have a heavy bio load in your tank. I wouldn't add any more fish even once the tank is cycled. The clowns alone req 20g min. I looked up blue tangs, they req 70 us gallons. That won't work in your tank. I'm surprised you do not have any ammonia or nitrite at this point in the tank after a month of no water changes. Are you using a salt water testing kit? Have you been testing on a reg basis? Doing small frequent WC's during the cycle process will not hurt the process and help keep the fish healthy.

Here is an article on Marine tank Cycling: http://www.fishchannel.com/saltwater...e/cycling.aspx

Let us know how things progress for you.

[Brad79]

Dano hit it. That tank is far too small for that many fish, even when it is fully cycled. The combinations are all wrong as well. 2 Centropyge genus fish are simply not compatible in such a small tank, and neither of them were appropriate for a tank that size anyway. The Damsles were simply a bad choice for a tank that already had fish, they are notoriously aggressive fish and will likely do more damage in that tank. That tank is large enough for the clowns and not much more beyond that, especially for such a small amount of live rock. I would strongly suggest you wait until you have done far more research on marine tanks before you jump into keeping one.