Fish dying

[RoyalT]

I have had 3 fish die and cannot figure out what is going on...

My tank contains:
feather duster worm
1 speghetti coral
mushroom polyps
10 blue legged crabs
7 lg snails
coral banded shrimp
red star
sand sifter star
20-25 lbs rock
blue damsel
metal haylide and actinic lighting
fluval 305
protein skimmer
35 gallon tank
fish that died:
small yellow eyed tang and cardinal purchased same time- died about 2 wks after purchasing, one morning tang was laying on side for awhile, then would swim around tank very rapidly, then lay on side again- by next morning it was dead. (We thought maybe adding one of our rocks might have stressed him out and also gotten sand in his gils?) About 2 days later, woke up and cardinal was also dead, with no physical sign of disease.

4 weeks later we purchased a tomato clown from lfs and 2 days after that woke up and it was dead also no sign of disease, acted healthy until found dead.

levels checked almost daily always correct also take water to be checked by lfs when changing water every 2 wks.
acclimate fish for 45 min with lfs water and our tank water.

noticed few days ago bristleworm (2-3 inches maybe? only part was out of rock) in the rock that was placed in tank right before first fish died... Could bristleworms be killing fish?

blue damsel still alive and well after 3 months (husband thinks we have a ninja damsel that kills other fish at night...)


Bad luck buying fish or am i missing something?

[fishbait]

bristle worms don't normally kill fish. people just find them eating on a fish after they died and assume the bristleworm did it.
the damsel could be picking on them and killing them, they are known for it
or the fish could be sick when you purchase them.

[Bifferwine]

Bristleworms would not have killed your fish. Nor would adding rocks.

The yellow eyed tang may have died from stress from being in such a small tank. There is no way you could successfully keep that fish in a 35 gallon tank. They need at least 150 gallons... Tangs need a lot of space and a lot of dissolved oxygen because their metabolisms are so high. They will get sick and die very easily in a tank your size.

As for the other fish, I suspect that it may be the damsel. Were there any signs of injury on the bodies? Blue damsels are highly territorial and aggressive and will often kill other fish, especially new ones that you just added. They are awful to have in reef tanks.

[Doc]

it could have been the damsel, or something else. How old is your tank?

-Dr Marco

[Doc]

I ask that because when my tank was about 4 months old. I was adding a fish a week and killing a fish a week. All my corals were doing amazingly well. I checked for mantis shrimp, I hung out all night looking for weird Sh!t with a red flashlight, I tore apart my rocks looking for some alien blood-sucker that was killing my livestock. I never found out that what was killing my fish was me. I was adding too much too fast. I gave my tank a break for 2 months. It was he!! for me to wait as I was not patient at all (still struggle with that after 2.5 years of this hobby). I needed to leave my tank alone to let nature run its course. After that, I was able to keep any fish I wanted in my 125 and have had great success. I have still lost fish, mostly because I push the limits of what is smart to add - again all me.

It could be that there is something killing your fish....or not. This hobby has WAY more questions than answers. If I were you, I would leave things alone for 6 weeks. Keep up on water changes and leave the damsel in there. See if it lives or dies. After 6 weeks, catch the damsel and return it to the LFS (or kill it, if you prefer - especially if it was the guilty fish) and start again. Just my . Best of luck to you.

-Dr Marco

[RoyalT]

our tank is about 4 months old also. i waited about 2-3 weeks after the first 2 fish died to get the clown...this is whats so frustrating about saltwater it could be so many things!! my blue damsel is only about 1 in long, could he really take on the others?

[Doc]

probably not. I would just wait another 6 weeks and leave the damsel. Seriously. It is not much fun when you cannot figure out why your fish are dying.

-Dr Marco

[Bifferwine]

I think a 1-inch damsel could have done it. They are evil.

[Doc]

I still say level the system alone and keep the one fish so the cycle keeps going.

-Dr Marco

[RoyalT]

LFS suggests that I do not have enough oxygen in the tank. He suggest that I get more current running threw the tank. Does not think a Blue Damsel could kill a Tomato Clown. Also, there were no war wounds on any of the fish that have died. Does this sound right?!?! Could it really be a lack of oxygen in the tank?