Have introduced a number of new fish to a 4 year old tank over the last couple of weeks. However in the last couple of nights a number of fish have been brutally murdered according to my parents.

The first to go were my two specimen black widows which at 4 years were large and in perfect condition. They were attacked and had their fins chewed to pieces, one was found dead, the other with its fins torn to shreds but swimming ok but has subsequently been finished off Now one of the rosy barbs is dead and also one of the blue botias.

I have got to act fast before the whole tank is destroyed. Problem is all the fish in there are community fish and all the attacks happen in the middle of the night when no one is around.

The fish that have been introduced are 6 mollys, 2 rosie barbs, 2 rosy tetras and 3 blue botias. Nothing there that are aggressive although I have heard since buying the blue botias they can be a real pain in the ar$e at times. However nothing has pointed to them being killers.

Before any of the above fish were introduced there were no troubles in the tank at all. However I have now lost two of the specimens of the tank and its gutting Plus others are starting to be picked off as well.

Any ideas bar sitting up all night waiting for an attack to decide which would be the most likely killer? Nothing watching the behaviour indicates anyone fish Its a turn of character at night when all is dark and no one is watching them

I need to act fast before 4 years of development of the tank is destroyed

Oh and the original fish that are left are 2 very large clown loaches, 3 leopard corys, a plec, 1 rosy tetra, 1 rosy barb and 2 white clouds and a red tailed black shark (of good size but very peaceful).

And its not water quality killing them off, currently have near on perfect water quality, tested just a week ago.

Something has tuned nasty and I need to find out what. Tia for any help.

 

Its highly unlikely its the red tailed shark, its been there for 2 years and lived with the black widows all this time in peace. Its got to be one of the newbies but like i've said none from that list I have put up are aggressive fish, not unless blue botias are killers rather than just a pain in the ar$e. Again though they are bottom feeders and it would be difficult for them to nip at fins as their moth is downward facing, it has to be a fish with a front pointing mouth to get at the fins while swimming, in my opinion anyway. Its possibly a molly as already had to kill one off for nibbling the dwarf gouramis (which I forgot to add to the list!) but just thought that molly was a one off as they are supposed to be the most peaceful fish you can buy

Also I know normal gouramis are highly aggressive and semi community fish but dwarf gouramis are listed as peaceful community fish and i've not seen one attack another fish yet.

 

The red tailed shark would have to have had a major change of attitude as over 2 years its never attacked one fish.

 

Cheers Mice but only have one tank. I think the only way to get the correct answer quickly is going be sitting in the lounge all night and wait for an attack. Time to get some stella in!

 

Territory issues with new fish I suppose could have upset the shark but he has been so placid, I just can't see it being him. The new dwarf gouramis seem too timid to do anything but with their bigger cousins being highly aggressive i'm tending to sway towards them having been perhaps interbred and leading to an aggressive streak inherited from their bigger relatives.

But then having seen a molly (which should never attack anything) attack the gouramis to the point where I had to take it out and kill it I would have thought the gouramis would have attacked back if they had any aggression in them, especially being a lot bigger than a molly.

There is literally no clear culprit from what I know about my tank and fish

 

Cheers for the replies going to phone the shop where I bought them from. I wish I had not added any fish now as losing the black widows wasn't worth anything, they were probably worth a fair bit as well with their size and fantastic fins.

Last time I ever introduce fish all at once and do it very slowly in future, big lesson learnt

 

Messiah I know of their reputation but like I say its lived with all the other fish for over two years with not even a nibble at anything.

 

Yeah I knew there was a risk with the blue botias not getting on with the clown loaches, but the clowns are again specimen size and massive compared to the blues so thought they would easily be able to take care of themselves. The clowns haven't been touched thank goodness as they are the daddies of the tank and my number one asset in the tank.

Going tio have setup camp in the parents lounge one night and sit it out if I want to get a quick 100% answer I guess.

 

Ciaran yes Tiger barbs are viscious, they are semi community fish at the max. However rosy barbs are not the same creature by any stretch of the imagination and are community peaceful fish generally.

LOL Jason it looks like i'm losing the battle here to keep my shark as i'm the only one sticking up for him! It better not be him as he is pride and joy along with the clown loaches so definately don't want to get rid of him.

 

Yeah i'm gonna do a night time check to see what happens. It could well be the shark if he has been over crowded by the new fish but its really strange that all the fish are fine all day swimming about around each other then at night when no one is about one of them rips the **** out of others. Something has flipped big stylee and when I find out who it is its gonna get bashed on the driveway! The state of the fins on the one surviving black widow before it was finally finished off the next night was shocking. I didn't kill it as it was only its fins that had been torn up, its body was untouched.

Whatever is flipping in there is one nasty piece of work thats for sure. In fact might send it to ajm when caught and he can put it in with his pirahna to have a play with

 

LOL yeah I gave up keeping guppies at the beginning as something had a taste for guppy intestines and I never did find out what was killing them. Would just find an empty carcass in the bottom of the tank minus its guts.

 

LOL @ Sith

Cheers guys, well just got back from parents and sat and watched them for ages while the mrs watched big brother and not one of the bu66ers gave any hint of showing aggression However the two new rosy barbs are far more frisky and lively than any of the other rosy barbs I have had and the black shark was doing his normal circuits and everything was staying well out of his way but he showed no sign of aggression and he actually cleaned the face of the plec very gently

Having checked the tank I have lost both specimen 4 year old black widows, one dwarf gourami (new) , one mature rosy barb, one 4 year old white cloud

One of the new baby rosy tetras has had his tail fin chewed to the point of being non existent but he is still swimming fine so have left him, although with him being weak I can see him being tonights first victim. The other remaining new dwarf gourami is very nervous and staying by the heater and pump. The killed gourami has been eaten to the point of non recognition and the remaining one had been hovering near it but not joining in the feasting as far as I know. The mature rosy barb was untouched however but just floating on the surface. Both black widows had had their fins chewed to the point of total removal. The white cloud has been totally eaten, was there this morning apparently and has vanished during the day so its not just night time now.

All the fish that have gone are mid water fish, none of the bottom feeders have been touched such as the corys or the plec, or the loaches or the shark. The top feeding mollys haven't been touched either.

Have no firm idea having studied them tonight, there was no indication at all Will have to see if any more go tonight and if they do then I will do the late night vigil tomorrow.

Beginning to wonder/guess if the two hyper active frisky rosy barbs are to blame, they are mid water fish and not acting as I would expect them to such as flicking their top fins up and down and swimming round in circles around each other, but it would be totally out of character for their species and they might be acting like this due to the current state of affairs.

Total nightmare having lost 4 year old fish, would be less frustrating if they had been the new fish, although no dead fish is good news but 4 years is a long time to get back in growth.