Annal fin spots... Mouth brooders???

[Magnum Man]

I remember ( barely ) 20 years ago, I used to keep rift lake Cichlids & the males had spots ( to get the female to suck up sperm, to insure all the eggs were fertilized in her mouth ) maybe I don't remember correctly??? anyway I've seen spots on lots of Cichlids, is that some sort of carry over feature, or did most begin as mouth brooders???

thoughts???

 

[GaryE]

Since you asked, mouth brooding isn't simple, and not all mouth brooders have egg spots.
Haplochromines tend to have the female carrying, and when she releases, it's over and done. That's where Mbuna are.
More complex mouthbrooding has the female picking up, releasing and picking up fry, for a couple of weeks.
There are different points in the process for the pick up - eggs or larvae.
There are also species that share the workload, trading larvae back and forth so both get to eat. That's one of those greatest show in a fishtank things to watch. I recently caught my Chromidotilapia nana doing that, on video.

It's evolved a few times, independently, since it works. The egg spots on Malawis are egg like, but anal fin spots are on a lot of fish.

There are other mouthbrooders - several Betta species do this, for example.

 

[Magnum Man]

I see a lot of what we used to call "egg spots" looking spots on Ram annal fins, but they are not mouth brooders as far as I know???

 

[GaryE]

No. But some of their closest relatives are. They are geophagines, and some of the Geophagus species are mouthbrooders, as is at least one Apistogramma.

 

[GaryE]

But they don't have the primitive kind of mouthbrooding Malawis have. My Satanoperca would fertilize eggs and then carry the small thin flat stones they spawned on the safer places ("Here, you, take this end. I'll get the other"). They didn't pick up til the larvae hatched. My Geos also laid the eggs in the standard way, before pick up.

So that theory of egg spots and Mbuna is a Lake Malawi fish thing.