Went from perfection to crash

[kimmysue]

I am very new to the hobby. I have a 75 gallon tank with wet/dry filter, canister filter, uv sterilizer, power head, and heater. I have lots of rock (not live rock) and large coral to give shelter to my fish. I started the tank in the spring; added 8 damsels (4 domino and 4 blue devil) and a hermit crab in May. My nitrates, nitrites and ammonia levels are perfect. My PH has always been low, but dropped in the past week to 7.9. I began adding buffer to raise the PH on Sunday. I have brown and green algae growing on the walls and rocks, which I clean off weekly or more. My hermit crab recently molted, I don't think that it is relevant, but who knows?!
Now the sad news, with a new tank, I was so proud to have all my fish survive the first three months of setup. On Sunday, I lost my first fish -a black domino. Now, two of my blue devils and one black domino look ill. The black domino looks less black, more light black or gray. The blue devils look like their scales are turning gray. All my fish, except the two largest black dominos (quite agressive) have fins that look frayed.
I am not sure if I am dealing with a disease from a PH problem, agressive fish, or something else. I think things started to go bad with my PH when I gave birth to a premature baby last month. I did water changes and testing, but must have missed a problem with my sleep deprevation and stress. Please help. I love my aquarium and I am so disheartened to be be losing fish. I was planning on adding a couple of clownfish this month, but now I don't dare until the problem is fixed.

 

[kimmysue]

Sorry, I just realized that I forgot to mention that my salt level is 1.023 and my nitrate tests come clear (0); nitrite clear (0) and ammonia yellow (0). I feed them one small pinch of flake food twice daily. Also, my ph went from 8.1 in May to 7.9 in August. I have been trying to fix it with water changes until Sunday. I added PH buffer due to the death of my first fish.

 

[beth]

The pH your had really was not bad for a FO tank. What is the pH now, and how fast did you try to reaise it.
Fish symptoms before death?

 

[kimmysue]

PH is 8.0 now. I have added a ph buffer per directions each day since Sunday. The package says it increases it slowly. Here is a photo of my latest loss

Thank you for any advice you can give me!!!!

 

[beth]

Stop adding the buffer. Your pH is fine now.
What were the symptoms of your fish?

 

[kevtheiris]

wonder if the two bigger damsles are attacking/stressing out the others. I had this problem w/ one of my yellow tailed blue damsels. he killed off 2 others before i realized what was happening. I put him in my hospital tank and the others went on fine. The attackees were missing part of their tail/side fins right before death. The bully damsel who i seperated just died last week when the filter i was using on the hospital tank crapped out on me, other than that he was doing just fine too.

 

[kimmysue]

All the dead or dying fish are small in size. They are being picked on by the other fish and try to swim away quickly, but end up losing. Their breathing is fine. The sick ones seem to hover in one spot before they die (near the surface of the water or the floor). They have been hiding more during the daytime recently. Some of the blue scales are turning grayish-silver on the devils and the domino's black scales were faded. All their fins are ragged. They don't float sideways until the end of their life. No spots on them, no redness that I can see. It seemed to happen overnight...but thats not to say that I couldn't have missed something. Their eyes were clear, gills looked ok.
I knew the larger damsels were bullies, but the problem seemed to escalate within the past few days. All the fish looked healthy until this weekend. It was a huge shock.

 

[beth]

I see. Your tank is suffering from aggression. Not much can be done about this except remove fish.
Damsels can be notorious bullies. How many do you have?

 

[kimmysue]

The LFS sold me 4 domino and 4 blue devils. I lost one of each so far with one more blue devil almost gone and a faded domino.
My guess is that clownfish will not be a good option for my tank now. I had wanted clownfish and a flame angel, but waited for my tank to be more established (aged). Where can I research to find options for my "aggressive" tank. My hermit crab is quite large and is not picked on at all - yet. I can see three, maybe four bullies in the tank of the six remaining.
Thanks for helping me diagnose my tank. I feel better knowing that it is disease-free, so far (knock-on-wood). I was panicked that disease had struck. I could kick myself for listening to the LFS and getting damsels. I wanted a quiet, peaceful, less stressful tank.

 

[beth]

They ain't called "devils" for nothin'! I have yet to be able to keep more than one damsel at a time.
Kimmy, disease could strick and it will unless you set up a QT. It will only be a matter of time. Sooner or later.

 

[kimmysue]

I have a 15 gallon rubbermade tub that I use for mixing the salt with the water. It has a heater and airstone. Can that be used as a quarantine tank, or do I need a seperate tub for medicating and housing sick fish?

 

[matt_m]

Damsels are evil. I have 5 of them. They were beating up the fish in my main tank. They are now residing in a 29 gallon tank with my 6" peacock mantis.

 

[sw65galma]

Originally Posted by matt_m
Damsels are evil. I have 5 of them. They were beating up the fish in my main tank. They are now residing in a 29 gallon tank with my 6" peacock mantis.

Don't feed the mantis until the damsels are gone