Fish health

kreblak

kreblak

FDA approval pending
Mar 13, 2003
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Allright, let us see who out there has a degree in marine biology. I just recently restocked my tank after an outbreak of Black Ich wiped out my prior fish population. The parasites are now dead. However, so is my bio-filter. So, I went to my LFS and purchased three damsels (two yellowtails and a domino) so that I could let my tank cycle again. Simple right? Wrong...

After 15 hours in the tank, one of the yellowtails is now dead. His body is strangely colored; black on the top half and blue on the bottom half. He was all blue with the yellow tail. His gills are ghost white, and actually look hollow on the inside (when viewed from the posterior). His fins, eyes, and scales are all fine.

The water shows ammonia and nitrates at 0. The salinity is 1.0225, and the temperature is a balmy 76 degrees.

So, what killed the damsel? Is it possible for a fish to die of shock from the transition into the new tank, or is it much more likely that the other damsels ganged up on him? Any theories on what could have killed him so quickly?
 
I don't have my degree yet, but I can take a stab at it. White gills may mean a blood problem, usually to much CO2 or not enough O2. Any caulerpa or any other flora in the tank? And as far a hollow body goes that could be just bloating from death or he could have been starving, which tends to cause bloating. How are the other ones doing? Did you medicate the tank at all to get rid of the trematodes? I have no idea why the fish would be discolored, in that discoloration usually affects the whole body, or at least in patches, not in neat sections.
 
I would guess that there's more than one cause here.

Shock can kill. If you salinity and pH differed widely from the LFS, that could kill. Or, it could weaken the fish enough that bacteria could finish it off. If the tank went without a water change for long enough, that could cause problems. Inadequate water agitation could result in O2 depletion, especially if there are other critters in the tank using it up.

I doubt that it's the other fish, since they wouldn't have had time to establish territories yet, so wouldn't really be fighting.

What else is in the tank? LR, corals, ect? Last water change?
 
There are several other inhabitants of the tank, 5 hermit crabs and 3 turbo snails. No flora, save for the green and brown algae that grows in the tank. The last water change was three days ago (10%).

Oh, and the discoloration was by no means uniform. The top half was black, but the line between blue and black was a splotchy, zigzaggedy one. The other two fish are just fine, as of right now.

About the trematodes, I kept the tank fishless for 21 days while treating with No-Ich Marine. No-Ich was designed for white spot Ich, but one day after the first treatment I was no longer able to view the ugly little suckers when I turned the filter off and let the tank sit for an hour or two. The tingle tells you it working! :rolleyes:
 
I'm sure a reaction to the medication was somewhat present in the fish, even if it wasn't the direct or only cause of death. The black could be a form of decomposition. Do you know exactly how long it was dead? The straight 15 hours or somewhere in between?
 
The fish were placed in the tank at 3:00 PM on Saturday. I went to bed at around 1:15 AM Saturday night, and all seemed fine. The fish were all upright and sleeping. When I awoke at about 9:30 on Sunday, the yellowtail was laying sideways on the crushed coral... dead. So, he wasn't dead for more than eight hours.

BTW, the medication says that it "completely biodegrades within 4 to 5 days, leaving behind no toxic residue or build up." The last treatment was done five days prior to the fish being added.
 
Change ALL the water in the tank. It would be wise to fill the empty tank part way with fresh water, clean any gravel or coral decorations, then drain and discard that as well. Finally refill with FW and mix the salt in the tank. Let it stand for a while, try one fish at a time.

When fish die as quickly as you describe, toxins of some sort are much more likely than disease. The description of the dead fish also sounds to me like a water problem. If you're new at this, check for other possible sources of pollution. Most of what you read on labels should be taken with (ha ha) a grain of salt. The "biodegradeable" claims are designed to get you to choose that product. Anyway, biodegradable into what?

Dump that water.
 
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