Sudden Unexplained Death In The Tank!

[Mr Melt]

Allright lads.

I just turned my aquarium lights on to discover a grisly scene: one of my poor gouramis was lying on the bogwood dead. What was worse was that her eyes and fins were gone, and she had massive gouge marks around the area of her (former) dorsal fin =(

RIP Poor Goldie =(

I'm concerned though; its only been a day since I added 2 longfin angelfish; could it be that they killed and ate my poor gourami?

Basically I have the following stocked in my Juwel Rio 180 (now at any rate):

x2 Rainbow Cichlids
x6 Congo Tetras
x2 Longfin Angelfish
x1 Opaline Gourami

I had assumed that this was compatible (especially after exhaustive researching online); but could it be that one of those fish decided to kill my gourami, or was it a natural death (and subsequent scavenging of the body)?

I should note that (apart from the Angelfish) the other fish have been in the same tank for the past week or so without problems; I have closely monitored the water conditions and they are fine (using API liquid tests). In addition I have checked all the individual fish in my tank and can see no injuries to any of them (including the Opaline Gourami, who is the exact same size as the late Gold one).

I will add a video of my tank (with all the current fish + Goldie) to show the fish sizes and temperament etc.

Please; any advice would be invaluable; especially to prevent another horrific discovery like this =(

The video:

 

[Mr Melt]

UPDATE - I just noticed that my Black Angelfish has a large part of his white longfin missing; I can only assume that its the Rainbow Cichlids that are the aggressors.

Why is that the case though? I thought that Rainbows were very peaceful cichlids......

 

[Mr Melt]

Really? No one has any idea =(

I'm really getting suspicious of my Rainbows, but as of this moment I've yet to see them catch another fish and take a bite out of it.......... they're just too slow in the 1st place.

 

[Mr Melt]

Well I've been monitoring them all day now, and it seems that there is no undue aggression occurring in the tank at present.....

......Still doesnt explain the gouramis death though...

 

[bristlenoseitplecoman]

All I can say is that the most aggressive fish in that tank are the cichlids. I think you might want to move them to a new tank or you could see if you are feeding the cichlids enough. Also THe angelfish might eat the tetras so be cautious with them.

 

[Mr Melt]

All I can say is that the most aggressive fish in that tank are the cichlids. I think you might want to move them to a new tank or you could see if you are feeding the cichlids enough. Also THe angelfish might eat the tetras so be cautious with them.

Thanks; I HAVE been starving them for the past 2 days (as I dont want too much ammonia buildup); I'll start feeding them a bit more now

 

[Mr Melt]

I decided to take the Rainbows back today, as I was fed up with their bullying and fin nipping antics towards the other fish.

Found out a very interesting fact: the LFS mislabelled them - instead of 2 Rainbow Cichlids they sold me 2 Blue Acaras......

No wonder they killed my poor Gourami ¬_¬

In the meantime, I have replaced the Gourami and the Acaras are gone; gonna browse online and search for a suitable replacement for the cichlids (maybe a Sajica, who knows).

PS - as a precaution, make sure the LFS has their fish labelled correctly; this has happened to me and my friends more than once!