Help, fish death!

[syncro]

I could some some diagnostic help.

The situation:
- Found 1 dead benggai cardinal fish stuck to the MP10 today
- Other cardinals and clownfish are NOT eating
- Introduced 9 cerith snails + 1 hermit last weekend (no quarantine)
- Prior to that, last livestock change was 4 months ago (from quarantine)
- No white spots on surviving fish
- Water params reasonable and stable
- Last weekend, installed an ATS (really just put a white plastic mesh in the sump horizontally and a light bulb)
- Water params stable, using controller for ATO and temp
- ph: 7.7 - 8.1
- Ammonia/nitrite/nitrate: 0/0/0
- salinity: 38ppt (I have been lowering at rate of 1ppt/week)

Have I introduced marine ich or velvet? Other possibilities?

Thanks!

[daniella3d]

I doubt it's marine velvet. did you put the water from the bag when you transfered the snails?

Your salinity is very high and it could be higher if you are mesuring it with a hydrometer.

Are you using a good calibrated refractometer to mesure your salinity? If not, your salinity could be much higher than you think it is.

Also what is your temperature? At high salinity the dissolved oxygen is lower and if your temperature is high and your bioload is high, some fish could die from lack of oxygen. How many fish do you have in what volume of water? temperature?

Originally Posted by syncro

I could some some diagnostic help.

The situation:
- Found 1 dead benggai cardinal fish stuck to the MP10 today
- Other cardinals and clownfish are NOT eating
- Introduced 9 cerith snails + 1 hermit last weekend (no quarantine)
- Prior to that, last livestock change was 4 months ago (from quarantine)
- No white spots on surviving fish
- Water params reasonable and stable
- Last weekend, installed an ATS (really just put a white plastic mesh in the sump horizontally and a light bulb)
- Water params stable, using controller for ATO and temp
- ph: 7.7 - 8.1
- Ammonia/nitrite/nitrate: 0/0/0
- salinity: 38ppt (I have been lowering at rate of 1ppt/week)

Have I introduced marine ich or velvet? Other possibilities?

Thanks!

[Aquattro]

I've run my salinity at 1.035 for several months without bothering the fish. While you should lower it, that won't cause the problem.

[daniella3d]

Probably would not cause a problem in its own but what if the temperature is high, combined with too high salinity, combined with low lever of oxygen due to too high bioload?

Originally Posted by Aquattro

I've run my salinity at 1.035 for several months without bothering the fish. While you should lower it, that won't cause the problem.

[syncro]

Thanks for the ideas daniella, Aquattro - good things to check.

I don't think it is an oxygen, salinity or overstocking problem.

- Temp is 24.5*C +/- 0.2*C.
- Skimmer running 24/7.
- Salinity is high, but stable. It increased over the course of a year - caused by evaporating refractometer calibration fluid.
- Lightly stocked and healthy: 3 cardinals, 2 clowns, inverts in 40g. Two weeks ago the cardinals spawned. I figured the unusual behavor was from the spawning.

Today a second cardinalfish is sick. His mouth turned white with a few short strings of white hanging off. Not sure if the strings are growth or his skin deteriorating. Tonight his mouth has turned red. Best guess is cotton mouth bacterial infection. Moved both surviving cardinals to hospital tank and started Maracyn 2 treatment.

Thoughts? Thanks for the help!