Strange Colombian Shark deaths

Bristlenose Fan

Registered Member
Mar 29, 2007
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We recently got a 120gal tank for our 3 colombian sharks(to relocate them from a 55gal). They have been in there for the last two weeks and seemed to be doing well. They were swimming all over the tank and looking good. In the 55gal they would just swim up and down the side by the filter.

But yesterday afternoon one of them went missing. I looked around and found him under a piece of dirftwood dead. He looked good aside from the fact that he was dead. No signs of damage or sickness. Then this morning another one had died, he was between a piece of driftwood and a plant. Then this evening we saw the last one die.

While he was swimming he was only using his tail. He would flop around after he would push off and have no control where he would go. He would flip upside down, which he didn't seem to like, and would try to get himself back right side up. He would sometimes pause, then sink to the bottom, when he would hit the bottom he would start swimming again. We watched him for about 5 minutes before he went under a piece of driftwood and stopped moving.

If have not seen anything like this before, all the other fish in the tank seem to be fine. And when inspecting the sharks, they all looked fine. No signs of damage or disease.

When we tested the water our parameters were greate.
pH- 7.4
Ammonia- 0
Nitrite- 0
Nitrate- <5
Temp- 27C
His tankmates are a large pleco (from the 55gal), 4 violet blushing sharks(3-4in), 1 small clown loach(2.5in), 1 small oscar(2in).

Any thoughts on what this could be?
Could this be related to salinity? I am not sure what too little salinity would cause.
 
How long did you own them previously?

Columbian sharks prefer brackish water when older. Young can survive in FW, but will eventually need brackish.

I had 2 that lasted 4 or so months and suddenly both died off, and 2 before that that died within a month, and I was told it was lack of significant brackish water(I only used 2 tea spoons in 20gallons).
 
yes, they are brackish but they can survive in fw, one of the LFS around here has one in a show tank 1 1/2 feet long and its in freshwater....
 
the do need brackish but i've had mine in full freshwater for 6 months... they're about 5-6" and are perfectly healthy...

they're currently being acclimated to small doses of salt.

are you using test strips?
how did you cycle the new tank?
 
I had mine in complete freshwater, and they would all mysteriously die. They do require brakish water as they get older, and most websites say that when full grown they require complete salt water, much like mono and scat.

http://www.aqualandpetsplus.com/Shark, Bull.htm

This site has a picture of a larger cat who was not kept in salt water. Im not saying that they have to be, im just saying i would hate to see such a beautiful fish end up like that
 
i really dont believe the lack of salt is part of that mystery. I've also kept mono sebae in freshwater.
 
when a fish is kept out of its normal environment (i.e. a totally freshwater fish in brackish settings, a marine fish in brackish settings, a brackish fish in freshwater settings) they are much more suceptable to disease. plus, at 1½ feet long they shouldve been on their way to brackish water, and eventually full marine.
 
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