Mouthbrooding in Coccina Complex Species
Most people label the coccina complex species as bubblenesters. However, there is an oddity within this complex, in which certain species (specifically brownorum and rutilans) have been known to moutbrood either in combination with nesting, or as an exclusive means of rearing fry.
My first species of wild betta, was B. Rutilans ‘green’. It differs from the standard form of rutilans by the iridescent green scales that cover most of its body. In the 'Betta Handbook', Goldstein writes:
"There is no information about its hypural plates or its origin, but Ralph Tran believes that it was collected in the same waters with the standard B. rutilans, that it may be a mouthbrooder , and that it probably represents an unnamed species."
Standard form of B. rutilans
Based on two years of personal experience, this has been exactly the case. Each time my rutilans pair would spawn, the male would hold the eggs until the fry hatched (usually after 48-72 hours). These fry then remained in the hollowed out log that they were conceived in, until they became free-swimming.
I am interested in attempting to isolate a sibling pair of B. rutilans to see whether mouthbrooding is isolated to only a few individuals, or is passed down onto the offspring of these fish.
Possible B. brownorum juvenile
I originally had a group of six B. brownorum, which was supposedly made up of three different pairs. Out of the entire group, only a single dominant pair ever spawned.
Each time this pair spawned, the male would only ever mouthbrood. He never made any attempt to construct a nest and his chosen partner seemed to have no issue with this rather unorthodox method of spawning.
Unfortunately, I only managed to pull one fry from that pair (I believe the rest were predated), and sadly I had to euthanise that group of fish before I had attempted to single out the breeding pair from the others.
I believed I had lost this single brownorum fry months ago and was sad to have perhaps lost that unique trait. However, recently I have had a juvenile in one of my grow-outs exhibiting an appearance similar to that of my previous brownorum. I am almost positive that this is indeed the surviving fry, and so am excited to see how it matures.
As a further point of interest, I was browsing the wild betta section of a French forum, and came across a statement about a possible mouthbrooding strain of brownorum. I also found some pictures of a male brownorum holding eggs. So it seems that there are brownorum on the other side of the world exhibiting this same behaviour.
All of this makes me wonder whether mouthbrooding in coccina species is triggered by genetic/environmental factors, or a combination of both. I thought perhaps the threat of other fish in the tank was what led to my brownorum male holding his eggs. Yet in the case of my B. rutilans, the male and female were always the only fish in the tank.
I think this is an area that often gets overlooked in discussions of wild betta species, but I thought it would be interesting to provide some of my experiences on the matter and to hear feedback from anyone who has experienced the same phenomena with any of their clarets.
Hailing from Melbourne, Australia, I currently keep and breed a number of species from the coccina complex.