odd cichlid behavior

First of all, welcome to the cichlid hobby.

Typically this shaking and vibrating is aggressive behavior though it can also be a sign of mating. Just because there is no attack carried out doesn't mean that it isn't aggression, in fact most of the dominance displays between fish don't result in any physical interaction, its mostly just posturing to the other fish. What it means is that your socofoli is showing the other fish how big, strong, and dominant it is. The color of a lot of cichlid changes with mood, personally I have a few fish that look best when they are really angry at other fish.

As far as using this behavior to sex the socofoli, the shaking doesn't necessarily make it a male.

2.5-2 inches is a large enough size for those fish to be breeding, though I personally wouldn't worry about hybridization quite yet. Given that your not sure on the ID of your fish it is still hard to judge the risk of hybridization. Also because you mentioned you purchased "mixed african cichlids" you should know that fish from those sorts of tanks are all too often hybrids.

If you have any more questions feel free to make more posts, this forum is an excellent tool because there are so many members with years of experience in keeping fish. For the fish that your aren't sure about the ID there is a section of the forum where people can help identify them.

Yes, he has begun chasing the other fish excessively, and only bothers the other yellow one when it gets in the way of the chasing. Still doing the dance. This poor victim/girlfriend has taken to hiding a lot and not looking too happy.

I don't want to over-crowd my tank, but should I try to buy more females to spread out the aggression? Female socolofis or any type? (and risk that they are male since its so hard to tell) or should I try to just separate the socolofi until I have a larger tank? I don't want him to kill the rest of the fish.

I'm planning on getting a larger tank when I move (in a few months) but here's what I have so far:

40g breeder decorated with pvp pipes, plants fake and real, a tower of broken flower pots, driftwood, and some aquarium furniture.

--8" chocolate albino pleco
--5" blood parrot
--2 yellow mbunas
--2 peacock mbunas
--1 socolofi
--I also have 3 danios as "chaser fish".

I filled in my profile with my guesses on what fish I have/ closest species to what they look like. I don't mind if they are hybrids, but from this point forward I'd rather buy identified cichlids.

thanks for all the help!

Here is your problem. You have a few different fish that tend to be aggressive in the best set-ups, in a tank that doesn't give them the room to behave naturally. I'm not sure what you mean by Peacock mbunas. Peacocks are peacocks (Aulonacara) and mbuna are different fish (socofoli is a mbuna). In a tank that size, you should stick with 1 type of mbuna, and have 1 or 2 males to 3 or 4 females ratio ( a species tank). You MAY also be able to get away with an only male tank, but no more than about 6 or 8 fish, and stick with peacocks and less aggressive mbuna like Electric yellow's (Labidochromis caeruleus) or Acei's (Pseudotropheus Acei).

In the situation your in now, the socofoli may pester the others to death. If you just remove him, that may help for a while but be aware that another male may take the dominant role and do the same to the rest.
I would do this: take the socofoli out and take him back to where you bought him. Hopefully they will take him and give your money back, if not maybe they'll trade you for another fish.
Hopefully that will give you time to get a larger tank and things will be o.k in the mean time.
While your waiting to get the bigger tank. Do some research into what fish you want to keep. Try to avoid getting hybrids . . And reearch how to mix mbunas, peacocks or whatever other fish you think you want. The Library section is a wealth of info. Please use it.

I have a 55 gallon tank and opted for the all male Malawi mix. Most of my fish are still young and I have some mixed in there that most people would not recommend. I have peacocks, haps., mbuna, and some Tanganykan fish too. But it's working for me. And within the next year they will be moved to a tank thats at least 150 gallon. It really is trial by fire, and I have the benifit of working with a fish store that will trade my fish at any time. So if I have a fish that's not working for me in my setup, I can trade him in for something else and give that a try. Now, I have a really good mix that is peaceful and VERY colorful. I really enjoy my tank.

Good luck. I hope this helps and feel free to ask lots of questions. Posting pics of your fish will also help people tell what you have, if they are indeed hybrids, and what you should or should not mix with them.

since I already have two of what look like Aulonacara (sorry, when I said peacock mbuna, that's what I meant) I will try to see if petsmart will accept the socolofi back in trade. My time for a return is long gone, as he didn't start showing this aggressive behavior until he was adjusted, and he was the last addition to the tank.

I would post photos, but I don't have any.

thanks for the suggestions.

edit: this picture is almost exactly what one of my peacock's looks like, only mine is very dull colored and has a few spots in-between the stripes.