Thoughts on why my fish are dying..

[Loreanny Medina]

Setup is a 46 gallon tank with a 15 gallon sump. roughly 50 gallons water volume.
tests with API show these levels:
pH - 8.2
dKH - 9
Calcium - 460 ppm
Salinity - 35
SG - 1.026
Temp - 78 degrees
Nitrite - 0
Phosphate - .25 ppm
Nitrates - 20 ppm
Ammonia - 0 ppm

These have been fairly steady for awhile.

We had 5 Chromis and 1 Scooter Blenny. Over the past few days each day 1 Chromis has died. First I found lying on the sand bed breathing heavy and he didnt move and I removed him to the QT tank and he died later that day. The next Chromis to die just disappeared with no trace so far. Third was exhibiting same symptoms of the first and was removed from tank and promptly died 5 minutes later. Now the Scooter Blenny was found laying on the rocks breathing heavy and not moving. I put him in the QT and now he is upright but still breathing heavy.

I read a post about the possibility of the hermit crabs attacking the fish while they sleep in the rock crevices so I moved the crabs to a different tank without any fish just in case.

During each of the individual deaths the other fish all seemed fine and had no problems.

I am awaiting the arrival of some chaeto to help export some of the nitrates and phosphate.

I change 10 gallons of water weekly right now to try to keep the nitrates down. I use RO/DI water.

Any idea what may be causing these fish to die in this manner?

[Reefing Madness]

When you say that things have been going ok for awhile, how long is awhile? Chromis are known for killing each other. Scooter Blenny probably starved to death. Unless you were able to seed the tank with PODS or you got him to eat sinking pellets or something else, odds are on starvation.

[Loreanny Medina]

I am not involved in the fish feeding. My gf feeds the fish. It is actually her aquarium I mainly handle the heavy lifting and setup etc. The livestock and what not are under her control. I actually have no idea what she feeds them.

edit: Ok she feeds the blenny some algae stuff and this other frozen food. He is still alive but doesn't look so hot at the moment.

[Reefing Madness]

I am not involved in the fish feeding. My gf feeds the fish. It is actually her aquarium I mainly handle the heavy lifting and setup etc. The livestock and what not are under her control. I actually have no idea what she feeds them.

edit: Ok she feeds the blenny some algae stuff and this other frozen food. He is still alive but doesn't look so hot at the moment.

Saltwater Aquarium Fish for Marine Aquariums: Scooter Blenny
Scooter Blenny is .....Outcome not good... They sift through the sand looking for Copepods. You can seed the tank, you can buy them to feed. Also try feeding the other fish Mysis Shrimp. But I stand by the Chromis killing each other, thats what they do, in tanks they chase each other around to the point of death.

[Reefing Madness]

Buy Live Copepods - Feed Your Fish! Ocean Pods(TM)

[Loreanny Medina]

I will try your suggestions for the Blenny either with this one or if it dies with the next one. Thanks

[Mad Mead]

I would think your SG - 1.026 is to high and Nitrates - 20 ppm is high as well
would like you to do a lager water change 50% to 60% to bring them down. A good SG. is 1.024 or 1.023 yours is at the high end of that scale. Fish to the most part can handle a higher but with your your full load of fish in the tank. my have caused your deaths. hope this helps
always read up on your fish to before bring them home. Just like dogs the fit is what count the most. You wouldn't keep a great dan in a Stud. Apmt. it just wouldn't fit...