[radiocognition]

I have an aquarium with 5 brilliant rasboras, a 4.5" green severum and a 5" black ghost knife fish. Over the last few days, I have noticed that the rasboras have had marks and missing scales - yesterday, I noticed that one had a quarter of its tail bitten off. I found this very strange because under normal observation, there was no agression at all between any of the tank mates and the rasboras. This morning I awoke and found one of my rasboras with its head bitten clean off. So now on to the profile of the two suspects

Barnabus - 4.5" Green Severum
My Severum is mostly peaceful, but he definatly is powerful enough to kill the rasbora, but I doubt that he would or could have done it without a bit of a racket. The last few days he has been more agressive in defending his territory but never towards the rasbora school. He has been raised in the tank since he was only 1.5" a year and a half ago. I am currently under the persuasion that if he wanted to eat another fish, he would have done it long ago. Also, he isnt that active at night, but that doesnt mean he couldnt have done it while my room lights were on

Zoiburg - 5" Black Ghost Knife
I know that Knifes have a reputation of being predatory, but I havent heard anything about Black Ghost. He generally leaves everything alone. From what I have heard, he is mostly a scavanger, but enjoys live foods. I have been feeding him sinkning shrimp pellents, but I really should be feeding him brine shrimp so he could be healthist. He is the newest addition to the tank, but he has been in for 4 months and it has only been in the last week that I started noticing the marks on the rasboras. Black Ghost Knifes are largely nocturnal, so he doesnt really have an alibi. However, mine comes out during the day, slowly scanning the entire tank for food every few hours.

Presently I think it was my knife that killed my rasbora, but if in any of your tanks you have had a similar experience - let me know. If I can, I will trade in the knife for a larger school of rasboras. It would probably be better for the fish because I dont have the room or time to maintain the brine shrimp tanks.
Any feedback would be great

 

[George Willms]

Severums wouldn't generally bother smaller fish. I'd definitely suspect the ghost knife of doing some night time hunting...

 

[joejoeg]

humm, i dont know i had a severum once that eate my parrot ! that was much bigger then him i watched it. a black ghost knife? they eat small fish by nature and i know he would eat a raspbora.

i believe its even steven ! heck , video tape the tank! maybe they will be caught! lol but first to go i would say the ghost knife , if it still happens then the severum. niether are great though because as the severum grose he will eat plants, and the ghost knife gets more or less a foot long and a 29 gallon is to small to say the least.

jordan

 

[Lupin]

Neither sev nor BGK should be in a tank occupied by rasboras. Sevs may be vegetarians but they are no exception to the rule of prey-predator relationship. Sevs can reach more than 8 inches and may eventually regard your rasboras as snacks. BGKs are also incompatible. They can reach more than 12 inches in size and as mentioned previously, they are also predators and will eat anything that will fit in their mouth.