Aggressive Red Finned Shark

[Cammy]

Hi guys,

I bought an already established 2ft tank that had some possibly incompatible fish, though they didn't seem aggressive at the time.

It had a male betta, blue three spot gourami, flying fox and the red finned shark.

At the time the only issue was the gourami chasing away the flying fox every now and then, usually when the gourami wanted to eat whatever the flying fox had found. They were all moved over to a 4ft tank and things seemed fine.

I found the betta close to death one morning and it died shortly after (of the cotton wool-esque problem). Strangely enough the betta had shown no sign of aggression to any other fish or received any aggression, likewise with the shark. Just the every now and then chasing away of the flying fox by the gourami.

However, the gourami now pretty much ignores the flying fox but the shark seems to be picking on it. I've been keeping an eye on it and it's been pretty low key stuff...until today. I observed the shark chasing the flying fox a lot for a few minutes but then everything would stop for quite a while, later on in the day I observed the same again. I've been out for a quite a few hours and the flying fox looks terrible. Totally lost it's colours and the stripe is barely visible.

Strangely enough, the shark and flying fox have been right next to each other quite a few times (while I'm writing this) and there has been no aggression at all now. Has the shark stopped now due to the quite visible damage to the flying fox?

Any idea why this is happening?

When I first got the tank I was told the flying fox was an Indonesian Loach. I checked out some pictures and decided it was more like a sucking loach or chinese sucking fish but have since found out is more like the Thai flying fox. The LFS person said the Thai flying fox has the black stripe that ends at the tail but the flying fox's stripes continues through it's tail (which is what I have).

I have some live plants, a cave ornament and two pieces of bogwood. Other fish are as above and the small plec and 8 danios.

I have found out that the shark is quite territorial but it doesn't attack any other fish. Also, the flying fox is visibly a larger fish.

What should I do now? Should one be removed (not really ideal) and which one?

Thanks for any help,

Cam

 

[Davo86]

Hi
RTBs, and Rainbow sharks and Flying fox are related species that do not tolerate their own kind or each other, as you are now finding out.
All require a minimum of a 50USG tank to reduce their aggression to a safe level, although all are generally fine when kept with fish that aren't of a similar bodyshape.

I would move the Shark to the biggest tank you have available

 

[Cammy]

Hi
RTBs, and Rainbow sharks and Flying fox are related species that do not tolerate their own kind or each other, as you are now finding out.
All require a minimum of a 50USG tank to reduce their aggression to a safe level, although all are generally fine when kept with fish that aren't of a similar bodyshape.

I would move the Shark to the biggest tank you have available

Hi,

Thanks for the reply. I was wondering if it could be because of the similar bodyshape but didn't think it would be because they seemed like quite different fish. I know not to keep more than one shark but had no idea that also meant the flying foxes too.

Some good news though is that the majority of the colour has come back to the flying fox and I have noticed the shark, gourami and flying fox all being very close to each other with none of them being overly aggressive to another, but I guess it will kick off at some point again in the future.

There goes my daft assumption that an established tank would come with less issues

Thanks again,

Cam

 

[Melman]

Hi,

I'm having exactly the same problem at the moment, i have a flying fox and a red tailed shark in a 260L, 4 foot tank. The shark regularly chases the flying fox and i have been told that this is because they are similar in shape and the RTS will not tolerate other fish that look like a shark. (i'm a bit worried that the shark will turn on my red line torpedo barbs when they get a bit bigger.)

If rearranging the ornaments/caves/bogwood etc doesnt work then you will probably have to re home one or the other, the shark being the logical one to remove

Hope you find a solution to the problem.

Thanks

Mark

 

[Davo86]

Hi,

I'm having exactly the same problem at the moment, i have a flying fox and a red tailed shark in a 260L, 4 foot tank. The shark regularly chases the flying fox and i have been told that this is because they are similar in shape and the RTS will not tolerate other fish that look like a shark. (i'm a bit worried that the shark will turn on my red line torpedo barbs when they get a bit bigger.)

If rearranging the ornaments/caves/bogwood etc doesnt work then you will probably have to re home one or the other, the shark being the logical one to remove

Hope you find a solution to the problem.

Thanks

Mark

Admittedly my RTB would chase my old torpedo barbs if one strayed away from the shoal, however if they were swimming together the RTB wouldn't bother.
That same RTB is now in a 125G tank with a Flying Fox, and it is the Flying Fox that is the dominant fish, chasing after the RTB when it sees it

 

[nickelplates]

People often advise a rearrangement of the tank decor to break up the offenders territory and this has already been mentioned. I can vouch for the fact that this can be surprisingly effective.

I had a rainbow shark/bridled minnow/red finned shark call it what you will in a community tank and he thought the whole tank was his territory and would try to chase his tank mates away, often relentlessly pursuing them round the tank. Most distressing were my corys who just didn't understand why they kept getting mugged .

I netted out the rainbow and put him in the dark in a bucket of water from the tank, then dropped the water level and just moved all the decoration which is artificial plants, rocks and flower pots into a new and more attractive arrangement (tricky if you have live plants I know). I let the inmates settle down in the new layout and then put the rainbow shark back, I guess he was out of the tank about three hours.

Within hours of doing this he adopted the bottom of one corner of the tank as his patch and while he will chase fish out of there as soon as they move away from his territory he will leave them alone, this was a year ago and he is is still behaving himself.

I know this is a different species but I thought you might like to hear from someone this idea has worked well for. Of course your case may be different and the RTB does have a fierce reputation for this sort of thing but it has got to be worth a try.

 

[Cammy]

Nice suggestion, I'll think about giving that a try if I see any excessive aggression again.

Since I saw the flying fox looking quite poorly he has definitely been ignored much more. Infact, I'm pretty sure I saw the shark swim away from the flying fox so maybe they took it to the limit and have now found a balance.

The gourami still chases the flying fox if he sees it eating something but isn't harassing the flying fox.

Maybe if I can obviously split the tank into sections and use your idea of removing and reintroducing the shark.

Thanks again,

Cam

 

[crazychris]

I had a RTB shark and Flying Fox once that used to fight like cat and dog. I took the flying fox to the LFS and guess what? Next day the shark died!

 

[San O Fisher]

As Davo86 said, a RTBS or a rainbow shark are all too territorial for that small of a tank. A larger tank would do him well as would lots of hiding places. I have not kept one since I was little but I had the same problems then.