Fish Deaths: Thanks!

Christopher D Kaufman kauf0010 at gold.tc.umn.edu
Tue Feb 28 12:06:56 EST 1995


Dear fellow fish people,

I've received many replies to my post and I wanted to thank you all for 
the great help and suggestions. There were too many to list, but know 
that we appreciated the time you took to reply.
In case any of you are curious, I'm including a brief synopsis of a couple 
replies that fit our condition. I should state that only 3 out of ~100 
tanks were affected and these were not particularly old or unhealthy fish. 
Also we have a continuous flow system, with incoming water going through 
several types of filters.

>steve johnson wrote:
>This sounds like gas bubble disease from supersaturated gases (O2, N2) 
>in the water. Cold water carries much more dissolved gas than warm water. 
>When the water is heated in a closed sysstem, the dissolved gases don't 
>come out until they hit the aquarium, or the fish. 

>Charline Walker wrote:
> Since colder water will hold more dissolved gas than warm 
>water (or water under pressure will do the same thing), could you have a 
>gas exchange problem. When our water is under too much pressure and runs 
>into the tank rapidly and there is no air bubbling in the tank, the fish
>suffer from "gas bubble disease" which is not a disease but is nitrogen 
>coming out of solution in the fish. The fish get bubbles, their eyes pop 
>out and the fish can die. 
>avoid this problem by slowing down the water flow and by bubbling air in 
>the tank at all times. It is something that hits different tanks 
>differently because each tank equilibriates differently. 

This description of 'gas bubble' disease fits very well with our problem: 
only a few tanks were affected, and those that were had reduced airflow 
from inefficient airstones. We have since decreased the overall flow rate 
in our system from 5 gals/h to ~3 gals/h and replaced all the airstones 
that weren't flowing properly. We won't know if this will help until the 
next cold snap, which looks to be this weekend.

Again, thanks to all that replied. 
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Chris Kaufman                     |  This space for rent |    
kaufman at molbio.cbs.umn.edu        | Inquire within       |
University of Minnesota           ------------------------
Molecular, Cellular and Developmental Biology and Genetics
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