Another reason to buy 10 or more 'Corydoras'

[GaryE]

It's a curious fact that what a cory species does here they may not do there. It's hard to generalize. My melini are shy, but someone else could as easily report that theirs doubled as used car sellers. There are a whole lot of factors that go into it.

I once watched a perfectly calm spawning of Apistogramma sp "Vielfleck" where one female laid eggs, and two males peacefully took turns fertilizing them. It was something I never thought I'd see, but did it mean anything about that species' overall behaviour? I never saw it again, and who knows if it was just a sort of glitch.

 

[anewbie]

It's a curious fact that what a cory species does here they may not do there. It's hard to generalize. My melini are shy, but someone else could as easily report that theirs doubled as used car sellers. There are a whole lot of factors that go into it.

I once watched a perfectly calm spawning of Apistogramma sp "Vielfleck" where one female laid eggs, and two males peacefully took turns fertilizing them. It was something I never thought I'd see, but did it mean anything about that species' overall behaviour? I never saw it again, and who knows if it was just a sort of glitch.

I've seen that with other cicihld; that usually happens when the female chooses a subdomiant male as her mate; the domiant (in this case means stronger) male can't be chased away and he does his thing... If the male she chose is stronger he will of course chase the other male away.

 

[Magnum Man]

so, this is a bit off track, of the bulk of the conversations, but kind of relevant to the 1st post... so, how many of the fish we typically keep are hermaphrodites???

I know it's possible for some fish to change sexes, if conditions are right, including when all the members in the colony, are the same sex...

in my breeder fish, for my Tilapia, an alpha female must have made the male jump out of the tank, and into my production tanks, anyway somehow after last years production I ended up with 5 breeding age females, and no males... kind of a bummer, so now I'm growing males again, of which I'll save a couple this year for sure...

so, while I wait, I have 2 larger aquariums, one with 2 females, and one with 3 females... a few weeks back, a nest mysteriously was dug, in one of the tanks... I'm sure there is not a male, and I didn't get any fry over the winter...

so, are some families of fish more prone to sex change, than others, or is it just extremely rare??? could it happen to Cories???

 

[Magnum Man]

if this is any indication, looks like the bulk of the ones that can change sexes, are salt water fish???

9 Species of Fish That Change Gender (With Pictures) - Wildlife Informer

Some fish have the ability to change gender during their life. Let's look at 9 species of fish that change gender and a few facts about each one.

wildlifeinformer.com

 

[anewbie]

I tried drinking salt water once; it didn't go well and i definitely felt like i had changed sex.

 

[Magnum Man]

Hmmm. apparently large mouth bass often change sex...

What fish can change sexes? - The Environmental Literacy Council

The Amazing World of Sex-Changing Fish What fish can change sexes? A fascinating array of fish species possess the remarkable […]

enviroliteracy.org

 

[GaryE]

Change sex, or carry the potential to be either? Maybe it isn't a change as much as it is one firing up as the other gears away.
I've spent years trying tricks to influence gender in fish that hatch with to be determined gender. It's all there for either, and just needs the right triggers for the body to decide. I've wondered if I've had intersex individuals, and if some of the older females I have faced later in life triggers for the male part of them.
Gender is complicated biologically, with all kinds of switches affecting genes. The rules of mammals don't work with a lot of fish. Temperature, water hardness, hormones in the water, maybe lighting periods, maybe diet... who knows?

The only true freshwater hobby hermaphrodite I know of is the Mangrove killifish (Kryptolebias (used to be Rivulus) marmoratus). Technically, it's brackish, but I have known people to breed it in hard freshwater. They don't need males to breed, although under some environmental conditions, males can appear.

 

[TwoTankAmin]

Lets not forget the reason why some fish school, it is a defense mechanism. Bottom feeders, fish with a downward facing mouth, are often food for predators which often strike from above. The bottom feeders first defense against such attacks are upward facing eyes. This is why many such fish use "dithers" to let them know how safe things are above. Smaller mid or top water fish being out and about tells the bottom feeder things above are likely safe.

If one has no fish in a tank which bottom feeders might see as a threat, they will be more relaxed and willing to "break formation." But as soon as they are alerted to danger they would regroup and, if scared enough, would scatter for getting under cover.

In order to keep ones schooling fish schooling what we need to have is some bigger fish, usually vegetarians/algae eaters which appear to be a threat but really are not. One of my favorite fish for this are SAEs or even redline barbs. They have the size and activity levels to be a bit intimidating, but they lack the appetite.

edited for typos