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[Zbrafish] Sick Fish

Chris Obenschain chris.obenschain at MarineBiotech.com
Tue May 16 11:25:31 EST 2006


Christian Lawrence's response to your query is a very good one and it is
always best to isolate potential causes of poor health, to start with
the appropriate water quality.  Zebrafish along with many aquatic
animals will often show signs of disease associated with increased
stress allow opportunistic bacteria to move in.  One item I would add to
this list is your gas saturation levels.  You mention the fish having a
bloated appearance swimming near the bottom of the tank.  While this
could be a variety of things it would be good to negate the potential
for gas bubble disease.  This is generally caused by a leak on the low
pressure side of your system allowing for supersaturation of the water.
In the wild fish will swim lower in the water column to allow for the
gas to be released from their systems however in captive tanks this is
not normally possible.  A quick diagnosis can occur by viewing the fish
with the naked eye as well as under a 10X scope looking for bubbles in
and around the eye or fins.   You can also check the saturation with a
meter.   If you don't have a meter check the DO and get back to me with
your findings.   

We will be glad to assist in any way we can.



Chris Obenschain
Business Development Manager
Marine Biotech
Phone: 301-651-3633
Fax: 301-497-7682

-----Original Message-----
From: zbrafish-bounces at oat.bio.indiana.edu
[mailto:zbrafish-bounces at oat.bio.indiana.edu] On Behalf Of christian
Sent: Tuesday, May 16, 2006 11:25 AM
To: Alistair.Reid at anu.edu.au; zbrafish at magpie.bio.indiana.edu
Subject: RE: [Zbrafish] Sick Fish

The veterinary people that monitor the list can better tell you what you
have (you list very common symptoms), but a more important question
the rearing environment of your fish.    

Zebrafish are very tough, and typically, acute outbreaks of disease like
describe are the result of fish being stressed in some way, most
and frequently by exposure to unfavorable environmental conditions.  You
cull, medicate, and treat disease symptoms any way you want, but you're
going to fix anything until you stabilize the environment.

I may be able to help if you supply me with the following info, offlist:

1. pH. What is your pH and how do you regulate it (addition of NaHCO3,
aragonite, etc.)  does it move widely over time?
2. do you measure nitrogenous wastes and what are they (NH3/NH4, NO2,
3. what kind of system do you have?
4. what do you feed?  How often do you feed it?
5. what densities do you keep the fish at?
6. how often do you do water changes?
7. where does fish water come from?
8. what is the conductivity of your water?
9. how long have you had the fish?  Where did they come from?  

These are just a start, but if you let me know what these are, we can go
from there.

Christian Lawrence
Brigham and Women's Hospital
Karp Family Research Laboratories 06-004B
One Blackfan Circle
Boston, Massachusetts 02115
Tel: 617.355.9041
Fax: 617.355.9064

-----Original Message-----
From: zbrafish-bounces at oat.bio.indiana.edu
[mailto:zbrafish-bounces at oat.bio.indiana.edu] On Behalf Of Alistair
Sent: Monday, May 15, 2006 11:01 PM
To: zbrafish at magpie.bio.indiana.edu
Subject: [Zbrafish] Sick Fish

Dear All,

We are new to the housing and care of zebrafish and are currently
experiencing a number of fish getting sick.
We have seen the fish become "bloated" and swim near the bottom of their
tank. In addition to this, they have also what appears to be "red spots"

on their underside.
We have isolated the affected ones, but would welcome some advice and
information on what the problem could be and treatment if available.

Alistair Reid

Head of Animal Services
John Curtin School of Medical Research
Australian National University
Canberra, ACT, 0200
ph:     +61 2 6125 5529

mob:    0407278626
fax:    +61 2 6125 4977

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