Zebrafish (Danio rerio)


Tropical freshwater fish belong to the order of Cypriniformes. Of Himalayan origin, they are becoming increasingly popular as research models.

The Comparative Pathology Lab is happy to assist you in both diagnosing sick fish or setting up a sentinel program to ensure the health of your fish. Listed below are the types of things you might see in sick fish as well as a brief discussion of our sentinel program for zebrafish.

Health Monitoring and Disease

Diseased fish often exhibit similar clinical signs for different diseases. Fish should be observed daily for abnormal behavior. Fish that appear abnormal should be identified and separated out into their own container (Always wear gloves when handling fish or their water). There are two broad categories of clinical signs; changes in behavior and changes in appearance.
Signs of Disease in Zebrafish
Signs of Disease
Poster provided curtesy of the FishVet Group

Changes in Behavior:

  • Loss of appetite
  • Lethargic swimming
  • Flashing and thrashing
  • Equilibrium disturbances
  • Swimming in isolation
  • Congregating at the top or bottom of the tank
  • Clamped fins
  • Changes in respiratory rate
  • Gasping at surface of water
  • Opercular flaring
These are all non-specific signs of stress and not necessarily signs of any particular disease

Changes in appearance:

  • Skin changes (hemorrhage, ulceration or masses)
  • Scale loss
  • Fin damage
  • Changes in color (loss or gain of pigment in an area or over entire body)
  • Ascites, coelomic distention (swelling)/ dropsy ("pinecone" appearance with raised scales)
  • Exophthalmia "popeye" or endophthalmia "sunken eyes"
  • Skeletal or other deformities, i.e. curved backs
  • Poor body condition

Diseases of Zebrafish:

RARC Comparative Pathology Lab Sentinel and Health Monitoring Program

Sentinel fish may be submitted quarterly, semi-annually or annually depending on consultation with your clinical veterinarian and whether or not you have a closed colony or are bringing in new fish. While PCR panels (IDEXX; Charles River) can be done on new fish to ensure you are not bringing in any diseases, fish held here at the UW rarely need such panels done on a regular basis. Our program involves the submission of 5-10 live fish (We ask that you submit a mix of healthy appearing and poor doing fish). We will euthanize the fish and divide them into those we will send for culture to a lab specializing in culturing aquatic species and those on which we will do gross necropsies and histopathology. The final report will list any infecting organisms as well as all lesions.

Contact: RARC Comparative Pathology, Lab Email: comp_path_lab@rarc.wisc.edu
Aquatic Species Submission Form

Ask the Vet

Zebrafish Working Group

Zebrafish users interested in joining the Zebrafish working group, please contact Marc Wolman
Email: mawolman@wisc.edu
Tel. 608-890-1962

Zebrafish may have a preference for colors that could increase the average number of eggs produced and the percentage of eggs that hatch. Studies have shown zebrafish show a preference for red and green marbles, but recently a brief study (Patty Oden, UAB) started to look at the color of marbles for breeding performance. In this study, red and clear marbles produced both a higher average number of eggs and a greater percentage of those eggs hatching. Not everyone uses marbles for breeding but that doesn't mean you can't use colors to your advantage.
Do you want to learn more about this?
Contact the vet: Dr. Pierce Sullivan, psullivan@rarc.wisc.edu

Developmental Stages
Olfactory Control of Spawning
Olfactory Control of Zebrafish Spawning
Male and Female Identification
Male vs Female Identification

Posters generously provided by Zebrafish Husbandry Association (ZHA)
and University of Alabama at Birmingham (UAB) Zebrafish Workshop

Resource Links