aggres­sion of sphaerichthys vaillanti

Inter­est­ing obser­va­tion, there is one pair that has its own ter­ri­tory and another trio– there are two females and one is dom­i­nant towards the other but they stay near each other and near the same male.
They used to fight viciously, and traded places as the part­ner of the same male, to the point one of them has slight jaw dam­age from the vio­lence.
Now they are not com­pletely peace­ful but they don’t try and chase each other out of their ter­ri­tory, one is aggres­sive towards the weaker one but it remains near it in the same ter­ri­tory unlike the past when the weaker one had to hide.
And there has been no breed­ing of any of these fish, maybe there is too much crowd­ing and aggres­sion.
Every youtube video seems to show a pair of vail­lan­tis in a com­mu­nity tank, maybe this is a good way to keep them since I saw a pair turn into a male bul­ly­ing a female when I removed the other fish in the tank.

Jacob, some ques­tions:
1. Have the health prob­lems of your fish been solved? And how?
2. How big is your tank in which you observe that aggres­sive behav­iour?
3. Are there other fish present?
4. How old are the vaillanti?

The fish are healthy, that only was a prob­lem when there was some bul­ly­ing and when I used the wrong water, the symp­toms went away when the fish set­tled in and the water was cor­rected (med­i­cine was used in that case which reduced symp­toms but the proper water seemed to make a big­ger dif­fer­ence than the med­i­cine– skin symp­toms dis­s­ap­peared with med­i­cine but fish were still inac­tive until the water con­di­tions were cor­rected).
The tank is 2 feet long, and 20 inches deep and high. It has about 25 gal­lons of water in it, it’s not totally full but it’s a Red Sea Max 130 which has 34 gal­lons of water, inl­cud­ing a 5 gal­lon sump I don’t use so I’m guess­ing 25 gal­lons is in there.
There are 5 vail­lan­tis, 4 parosphromenus and 7 cey­lon dwarf barbs, they don’t seem to bother the vail­lan­tis, all of these fish ignore each other except for the intra spe­cific aggres­sion between the vail­lan­tis and some­times between the paros.
The vail­lan­tis were about one inch when I got them this sum­mer, so maybe 4+ months since then.
They look full grown, though I’ve read it takes them a long time to breed, that they mature slow.

You may have a sit­u­a­tion in which you’re actu­ally see­ing agres­sion between females. Sub­dom­i­nant females will adopt male col­oration as a means of decreas­ing their threat to the dom­i­nant female. Aggres­sion between males is not unheard of in this species but most intraspecies aggres­sion is between females. I’ve kept them quite suc­cess­fully in groups and in pairs. To max­i­mize their pro­duc­tion I would keep a pair or a female with two or three males. Be sure that there are plenty of hid­ing places so that any fish get­ting picked on has a place to hide.
Mark

One male died, the only expla­na­tion since all other fish look fine is that it was mouth­brood­ing and that stressed it.
I don’t even know if it was that male but there are only two and one was seem­ingly mouth­brood­ing for a few weeks. Never saw any babies but there are so many fish in this tank they eas­ily could have been eaten right away.
Or the male was hid­ing and not eat­ing for some other rea­son, but it looked like mouth­brood­ing.
Can that process really stress them enough to kill them not that long after?
There were sev­eral days after it stopped appar­ently mouth­brood­ing and when it died, almost a week.
Never looked sick and no other fish shows stress.

Jacob wrote: (…) Can that process really stress them enough to kill them not that long after? (…)

Yes, to all we know it can. But in nature after hav­ing released the young, not before. We have not solved all aquarium-​problems of the choco­lates up to now. Even experts who suc­ceeded in breed­ing them report about sin­gle sud­den weak­nesses and deaths. I am afraid I can’t tell you more. A week ago Horst Linke told me of sud­den deaths of his Vail­lants. He could not say why.
How easy are the licorice!