Saltcorner
By Bob Goemans
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Bob Goemans corresponds with Haydn Gopsill

Haydn Gopsill writes...

Hi Bob

I hope you don't mind me contacting you again, but I have seen some interesting behaviour from some wrasses in my aquarium.

I have 4 Macropharyngodon bipartitus bipartitus (Vermiculate Wrasse); 3 females and 1 male and had added them as a group of juveniles about a year ago. One has recently changed into a male and has been dominating the females, but not with any aggression.

Yesterday, at approximately 16:00 in the afternoon, all four collected at the surface of my tank, which is about 500 US gallons. One of the females would swim along the surface with the top of its head out of the water and thrashing its tail on the surface making a lot of noise and turbulence. This would attract the male who would follow her closely in the same way, head out of the water and thrashing it's tail. After a couple of passes, the male and female would split and swim normally.

Then another female would start and the process would repeat. This went on for about 5 -10 minutes. If I tried to get close to the tank they would just stop until I withdrew.

I assumed it may have either been spawning or pre-spawning activity, but according to sources on the web and in books, these wrasse are substrate spawners, with the female making a 'nest' and the male diving into the substrate to 'impress' the female.

Hence the contact, I'm hoping you may be able to point me in the direction of a site or book that will give me some ideas.

Again thank you in advance for taking the time to read this email.

Regards

Haydn Gopsill

England

Bob replies...

Hi Haydn,

Interesting behavior and could be a mating/pre-spawning activity, a defining of the sexes, or just include me in your harem activity. Since I'm not sure, will contact a friend that might help answer your question. - Have done so, and have the following answer from Vincent Hargreaves - "Re the Vermiculate wrasse: This is not pre-spawning/spawning activity - they spawn in nests. I suspect this is a 'mild aggression' activity to decide which of the females will become a secondary male. The primary male will allow a dominant female to become a secondary male in a harem. The trashing at the water surface only serves to simulate aggression. The theory is that the most dominant female will become a secondary male. Probably the thrashing at the water surface is only apparent because it is an aquarium. In the natural world this may not occur."

Hope this helps,

Bob

Keywords:

Fish Behavior

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