dundadundun - I found this after I read your post about your redtail shark episode.
"As they are not aggressive, they can be kept in any community tank big enough. Their active behavior might stress some sensitive species like dwarf cichlids and prevent them from spawning. They should not be kept with Red-tailed Sharks (Epalzeorhynchus bicolor) unless the aquarium is large and well planted, because that species is very aggressive towards all its relatives."
Just to throw my 2 cents in...I have 3 SAEs in my 45 gallon tank and they are wonderful fish. they are about 3 inches long now and have took care of all the BBA within a few days of entering the tank. I have never seen any kind of aggression between themselves or otherwise. They are always together and are really cool fish.....
pinkertd: i definitely agree... and i was aware of the possible issues, and my tank was planted. the issue was what is a large tank. i found out the hard way. these guys were in a 50 gallon planted tank, and i can say although some consider that to be a large tank it is not nearly large enough to keep a redtail and an sae. i would not try with a rainbow shark either with that size tank, but i have not yet proven that to be an issue .
I had a Siamensis (Crossocheilus) in with my Beta and Harlequin Rasboras, but after a few months it began nipping the fins on my Harlequin Rasboras and once in awhile, my Beta too. It seemed to be doing so during the dark night time hours. I finally gave it to my daughter who also has one that has never nipped at her fish. He/she doesn't seem quite as aggressive in her tank, but lately it has nipped the fins on one of them. I originally purchased this fish, because it is supposed to be active, but non aggressive. As well, a great algae consumer, which he/she certainly is! I now have three Oto's and they are wonderful and fun little fish! : )