Blue/Green chromis not doing well

[DanielJay]

I have 1 blue/green chromis in my 125g display tank and it is not doing well. (All other fish in tank are doing well) At first the fish stopped swimming and was hanging out near the bottom of the tank and wouldn't eat. A few days later I noticed that the fins were getting really beat up and disappearing. Now the fish will swim a little as close to the top of the fish tank surface and still will not eat. I usually feed flake food and occasionally mysis or brine shrimp. I have had the fish for 4 years.

I noticed that the system salinity had dropped from the usual 1.025 down to 1.021 or so. Over the course of a few hours I raised that to 1.023 and then last night when I checked again it was up to 1.024.

I will also add that on Sunday night I noticed that one of my MP40's was making a ton of noise when turned on. Come to find out the magnet on the wet side split open and the entire inside of the MP40 wet side case was rust colored. That has since been removed from the tank. I contacted EcoTech and they are warranty replacing that wet side unit. I did a 30g water change to the system which has about 275g in total water volume.

Other tank mates:
1x Blue hippo tang
1x Yellow tang
1x Yellow eyed kole tang
2x Ocellaris clownfish (captive bread and have had them the longest next to chromis)

Not sure exactly what I should do. Is this "old age"? Should I remove the fish from the tank as to not infect other fish if it is an infection? Any suggestions?

 

[Brian01]

electrical current? maybe?

electrical current? maybe?

An exposed magnet (any magnet really) in salt water will induce electrical current. Usually this is not an issue if the magnet is static, but if its being driven to move, maybe not? I'm guessing a bit here, my physics is a little rough in this area, but it seems possible, and if the magnet is exposed this could increase the issue. I really have no idea if the magnitude of the current will be sufficient to cause issues, this is where I'm guessing, its not like having a direct connection between your tank and your mains (a big plus of those vortechs). Anyways, the reason I'm on this track is that stray currents have been associated with onset of HLLE and some other tissue degradation, so maybe? I would have expected the tangs to be hit first, but that's not certain. If this is the case, you should hopefully start to see recovery. This does not explain the problems with salinity levels though, so something else may be at play. Did you notice any unusual loss of top up water? Is there any way your tank could be leaking without you seeing it? Tho this sounds like a lot of water leaking.

Regardless if my idea is possible, I'd say keep up with the accelerated changes as there may be various heavy metals from that magnet that are now in the water from the corrosion, and if bacteria didn't start the problem they are likely on the fish now, so treatment/isolation is the safe course, if you can do it. I wouldn't think old age, although it is possible of course, these fish can get well over 10 years is aquaria.