Paternal mouthbrooding in the chocolate gourami Sphaerichthys osphromenoides (Osphronemidae)

[John q]

So according to this study it's the Male fish that takes up the maternal care for this sp and not the female as previously thought. Why is this groundbreaking news, well if true it appears we've been mistakingly sexing chocolate gourami for years.

I'm guessing this will ruffle a few feathers amongst the experts.

Quote:

"According to our observations of 32 spawning events, parental care in this species was always performed by the male. Our visual observations were confirmed by video and histological analysis. This suggests that the sex in this species has probably been misidentified so far. We argue that the putative “females” (previously defined by external features) were in fact males, and that there are probably no exceptions to male parental care in osphronemid fishes."

Paternal mouthbrooding in the chocolate gourami Sphaerichthys osphromenoides (Osphronemidae) - Environmental Biology of Fishes

We examined sexual dimorphism and parental care in the chocolate gourami (Sphaerichthys osphromenoides) by visual observations, video recording of spawning, and histological analysis of the gonads of individuals in which spawning and mouthbrooding was previously observed. S. osphromenoides is...

link.springer.com

 

[Wookii]

I've got no idea when sex mine are, they all look completely different from one another now they're fully grown!

So everything is opposite to what we think - so it is the females that colour up with red etc, not the males, and it is the males with the enlarged throat and more muted colours, not the females?

 

[John q]

So everything is opposite to what we think

Not sure everything is opposite, the anal fin shape seems to still hold true but reddening fins seems to be a trait of females.

One of these individuals had a rounded anal fin, the base of which became reddish in colour during spawning. This individual never picked up eggs after spawning. We labelled this fish as No. 1. The second fish had a more elongated anal fin and a different colour pattern, in particular more contrasting white stripes on the body. This individual incubated eggs in the mouth after spawning in all cases. This fish was labelled as No. 2.

Histological analysis showed that the first fish (No. 1, female) had ovaries and the second one (No. 2, male) had testes.

They go on to say about colouration.

Colouration, fin shape, body size and proportions are commonly used for sexing in chocolate gourami. Linke states that the identification of the sexes in this fish is not difficult, because the dorsal fin in males is pointed, and in females is smoothly rounded (Linke 1991: 123). Sandford suggests that this rule applies not only to the dorsal fin but also to the anal fin, and notes that females are more robust than males (Sandford 1987: 26). Vierke wrote that males are larger (Vierke 1988: 158). According to van den Nieuwenhuizen, males and females have different head shapes (Nieuwenhuizen 1956: 31). Richter considers as a reliable indicator of males the presence, in contrast to females, of white margins on fins (Richter 1983: 106). Riehl and Baensch point out yellow margins on the anal and caudal fins of males (Riehl and Baensch 1985: 644), and Vierke believes that females also have margins on the anal fin, but slightly weaker (Vierke 1988: 158).

Unfortunately, none of these characters appear to be universal or consistent. For example, Geisler notes that although the reddish colouration of the anal fin is considered to be a feature of males, along with the elongated upper and lower caudal fin rays, sexing by these features is unreliable because colouration is variable and females may also have slight elongations of the fin rays (Geisler 1954: 54). According to our observations, reddish base of anal fin is characteristic for females, but not for males (in contrast to Geisler 1954).

They seem to base the miss identification of sexing on people assuming the caring sex was female.

All known descriptions of chocolate gourami sexing and breeding were published in aquarium literature or passed on by word of mouth. According to many amateur breeders’ observations, the eggs were typically incubated by the less colourful individual of the spawning pair. Apparently, based on knowledge of general trends, the observers decided a priori that the caring sex was female

So it would appear according to this paper that the more colourful gender in chocolate gourami is the female. 🤷

 

[bazz]

So it would appear according to this paper that the more colourful gender in chocolate gourami is the female. 🤷

I think it is has been widely known for a time along with the male mouthbrooding for the case of the congener Sphaericthys Vaillanti, so it would all make sense.