Loaches Online Forum

I am considering adding a red-tailed black shark (Epalzeorhynchos bicolor) to my well-established community tank, but I am a bit hesitant due to the possibility of territorial aggression from the shark towards my other fish. I have a number of clown loaches, various botiine loaches, three large featherfin catfish, some corys, some rainbows, and some tetras.

Yes, it is a big tank, and it is well maintained. Crowding isn't an issue, nor is a lack of hiding places. This is a tank that is set up with loach and catfish needs in mind, so there are a large number of hiding spots of all sizes and shapes.

I'm hoping that someone who has had experience with these fish, particularly with mixing sharks and loaches, or sharks and synodonis catfish (or both) can let me know whether or not I have anything to worry about. All of the research I have done points to sharks being highly territorial to the point of being aggressive, but the behavior I have observed at the LFS and on youtube videos doesn't seem to support this.

Expert advice, please?

The Red Tail is probably the most aggressive of the 'Sharks'. However, I have heard of them coexisting with Loaches that are pushy enough to claim their own space. Toward other species, higher swimming fish I think these 'Sharks' are OK. Except for other 'Shark' shaped fish like SAE, and probably Red Line Barbs.

It would help if there are some spare caves. The Red Tail will usually claim a cave, then defend the area in front of it. If the cave is open toward most of the tank then the 'Shark' might try to claim more of the tank. If the cave opens to a small area, perhaps defined with more rocks or driftwood then the territory claims are limited to that area.

Thanks for the information. It certainly gives me some good food for thought.

I haven't made a decision yet, but at least I am better educated now.

We had both RT & rainbow sharks over the years, 1 per tank. They were often aggressive with corydoras, body slamming them into the substrate, killing at times. Corys don't really seem to understand the concept of territories like loaches do. Lots of caves helps. Sharks also chased schooling fish like barbs that would go near it's cave entrance or mid-water during feeding but no harm done.

Thanks for the info.

After reading quite a number of stories similar to yours, I've decided not to add a shark to my tank. My tank is a pretty stress-free place (as far as I can tell) for the fish, and I'd like to keep it that way.

I agree with the second answer. In my experience, they only seem to chase bottom feeders.

of course, not adding them in worry of altering the dynamic is probably a good idea. I have a cousin who had a very vicious black skirt tetra... only 1 out of the 4 was mean to everyone so it shows that you can say a species is "nice" and then get a bully. it can happen!

i have added a red-fin shark in a 45G, that is home to a couple of clown loaches. They are bigger than he is, so I will keep my fingers crossed. There is also a large pleco and different tetras. I did add 3 red seerpae tetras, but didn't see them when I went back the next day! I am hoping they are hiding, but could they have been killed????? I hope not!!