http://forum.aqua-fish.net/ A forum devoted to aquarium fish, plants, techniques and fish keeping as a whole. en http://forum.aqua-fish.net/?topic=compatibilty-problems-help-#1 I have a very large community tank, and am having problems with some of the fish. Something in the tank is attacking, killing and eating our male guppies and our neon tetras. These are the fish we have in the tank: 2x shrimps 1x pleco (only a small youngster at the moment) 3x male guppies (2 have been killed) 9x neon tetras (2 have been killed) 4x marble mollies 4x gold sword tails 5x blind cave fish 2x young silver sharks 4x Kribensis (2 male, 2 female) Every time we have bought new fish for the tank, we have sought the advice of the fish shop owner and made sure any new ones we buy are compatible with what we have already got, but obviously somewhere along the line we have been given bad advice. I have tried to watch the tank and see if any of the fish are aggressive towards each other, but never see anything happening. I have had a good trawl through the internet and the only thing I found was that the kribensis sometimes find guppies a delicacy(I am not happy about this as was told at the fish shop that they were happy to live with all small fish, inluding guppies). But that still doesnt expliain the neon tetras being killed, as they are supposed to live well with kribensis. Although as the silver sharks get big they could well swallow small fish like tetras, they are still very small at the moment and to be honest, seem very placid. All the other fish, as far as I can find on different websites, should be happy to live with each other. Does anyone have any advice, or can see from the list of fish above, which are responsible for killing and eating the tetras and guppies? When the fish are dead, it literally looks like their tails have been ripped off, so its obviously a vicious attack going on. Please help if you can! cazzywoo 2010-03-30 http://forum.aqua-fish.net/?topic=compatibilty-problems-help-#2 IMO the kribensis look favourite for the attacks, you have two males and two females in there, have they paired up ready for breeding. If they have they will become highly territorial. I have a full thread on this behaviour on my site which you can find in my signature mickey 2010-04-01 http://forum.aqua-fish.net/?topic=compatibilty-problems-help-#3 also as the silver sharks get bigger guppies will be mouth-sized treats for them too. weirdartist 2010-04-11 http://forum.aqua-fish.net/?topic=compatibilty-problems-help-#4 The silver sharks are quite aggressive. irwin id 2013-08-03