Our lab is doing zebrafish research and my job is to maintain the health of zebrafish. I found a female fish with a very big belly so I let her mate with another male. However, there was no egg came out when I checked it the other morning and the belly remained big. Does anyone know what cause this problem? Should I do a belly massage to help her strip the egg? If yes, how to do it?
Hi Amanda.
First of all, you have to make sure your fish are in the reproductive stage.
Look at reproductive behavior.
Do you have a good male fish?
If all these steps were correct.
then, You have to stimulate reproduction.
increase the temperature at 28 ° C. Fish are not stressed and feed were not stopped.
you should put the broodstock in the net basket.
Because after reproduction, the broodstocks will feed their eggs because of their energy demand.
Zebrafish eggs are very tiny and you should look carefully at the below and wall of tanks or aquarium.
best regards.
What you describe sounds like an egg-bound female. It's an overproduction of eggs. Best is to try to set her up with 1 or 2 males again to see if the eggs are released, but most of the times this will not work.
You can take her out on a wet paper towel and cover her with a wet net to stop her from jumping, next carefully massage the belly (not covered by net) from front to back to release the eggs- it normally takes 3 or 4 gentle massages. Do not press to hard, and put her back in the water if it does not work for a later try. Unfortunately, even if the eggs come out we often see that he females have problems laying eggs in the future and become egg-bound again.
This seems to be strain-specific, we see egg-bound females mostly in the TL/TLF strain and rarely in AB. We keep TLFs at higher density and feed them more carefully to prevent them from becoming egg-bound.
I agree that it sounds like your female is egg-bound. Basically, the ovaries are producing eggs but the female has stopped releasing them, perhaps because the ovarian ducts are blocked and the oocytes are not reabsorbed efficiently, hence the increase in the size of her abdomen. It can be painful for the fish and in extreme cases can cause the skin to start splitting.
When something is off with our fish, the first thing I do is check all of the water quality parameters. Next, look at other parameters like food and light. You could be seeing this response if you have changed the type of food you are using, if the food is very expired, or the female is obese or has not been bred very much (especially if you house according to gender). Also, check the timer on your lights to make sure that it is working properly.
Most sources recommend gently stroking the abdomen from head to tail, massaging or squeezing the abdomen. This is very similar for procedures used for egg stripping for in vitro fertilization (https://youtu.be/ziNAXS1E0vE). You can do this with or without anesthesia (I usually choose without since it is fairly quick). If you choose to go without, make sure you use a soft net and keep her in it during the massage. You will know if this works in a relatively short amount of time after she has been returned to her tank and/or recovered from anesthesia.
Hi Amanda,
If this is not an extremely important genetic modified zebrafish that has taken someone ages to produce and also can`t be reproduced again. I can only recommend you to do the most human thing and let it rest in peace.
Kind regards,
Simon
I hope this link will help you
http://zebrafish.no/wp-content/uploads/2008/09/zfish-husbandry-review.pdf
regards
Breeding zebra fish can be a tricky process and need high levels of patience. When the female fishes abdomen swells, it is the sign that the fish is ready to lay eggs and breed. Isolate such females from males for at-least 2 days and feed them nicely. The selected males for breeding must be isolated from females as well and bred well similarly. During this time set the breeding apparatus which can be made easily. For preparing the apparatus you require a medium size tank and a small tank with smooth wire mesh covering it. Place the small tank inside the medium size tank and cover the mesh cover of the small tank with some pebbles and moss. After this is done transfer both females and males ready to breed in 3:1 ratio into the tank, say by evening 7.00 PM. Keep the fishes overnight and the next day by 10/11 PM remove the adult fishes to the main tank. By this time the chance for spawning in almost 95% and you can see fertilized eggs laid inside the small tank and to make sure, take it out and view under stereo zoom microscope.
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