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Discussion Starter · #1 ·
Hi, have a tropical planted (obviously) tank - new to plants - 20 gal long. My question involves two fish who seem to have developed a feud. One of the antagonists is a rainbow shark (epalziorhynchos frenatum - I believe), male and a male Betta. The shark was in the tank first and I added the Betta (love their feisty little personality) - there are various tetras in there too. At first the Betta just hid and was shy and everyone left him alone. Then he decided it was ok to be a male and apparently his testosterone kicked in, because after a week or so, he decided to nip the shark. Of course this led to the shark whipping around and biting him back and chasing him around the tank. This has been going on for days now, and they both do it. The Betta will hide in the myrio and just hang there and the shark comes seeking, then the chase then the bites. Patience, I'm coming to the question.

Is the shark being a little b*st*rd and could he really hurt the Betta (or vice-versa?), or is this play behavior?? I've seen various fish play in my tank and chase each other and have mock battles (especially when I had rosy barbs - some grand mock battles took place!), and chase each other. But the Betta's beginning to look a trifle shopworn.

TIA

OSD:confused:
 

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r'bow lover
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Well, rosy barbs and other group spawners will do this regularly. It's to establish who gets to breed more often. Totally normal and natural for them. Barbs, danios, tetras, and other schooling fish do this.

The betta has a natural aggression, IME all anabantoids do. I've kept and bred dwarf gourami and microctenopoma and both are quite athletic in their aggressiveness- lots of chasing, flaring, and sometimes nipping on each other and others.

As for the shark, they too are quite good at chasing, usually it is like the barbs and to show dominance. When two are evenly matched these fish will tail-whip and side shimmy each other. A lot of people see this and then a chase afterwards which can result in nipping. I'm guessing that the shark sees the betta as a fish he needs to compete with since the betta is doing the same. Unfortunately, the betta was selectively bred to have those long fins... therefore what may be innocent dominance battles tend to turn ugly due to the fact that the betta has more drag than it's aggression realizes... it picks fights it normally would but cannot "make a break for it" if he's over matched due to the fins. I would imagine this behavior would keep occurring and the shark will indeed overwhelm the betta eventually- likely getting so many various nips in that it causes disease for the betta.

I'd separate them.

HTH! GL! :)
 

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Discussion Starter · #3 ·
Six, thanks very much.

It sort of saddens me though, they are BOTH such gorgeous fish! And the shark is an algae-destroying vacuum; my tank has never been so clean.

<Snip>When two are evenly matched these fish will tail-whip and side shimmy each other.<Snip>

Yes, I've seen this and now I noticed one of that poor Betta's fins is pretty torn up. Damn. Oop - dern. Too bad I can't buy them a couple of beers and tell them to just chill!!:|
 

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You're most likely going to have problems with that "shark" no matter what else you put in the tank. They tend to be aggressive and the more they mature, the more intense it becomes.
I also don't believe he'll keep eating the algae as he grows, so you may want to make a decision one way or the other now before you get more attached to him, or the Betta.

I agree, they are both beautiful fish, so it's not an easy decision to make.

Keep us posted. :)
 

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Discussion Starter · #5 ·
Wellll, sorry to say I DID have to end up taking His Highness the Betta out of the big tank and putting him in the 5 gal hex (don't get me started on that piece of:flame:...). He is MUCH happier, now that his fin is growing back in.

And the shark is also happier since he knows the tetras and doesn't have to compete for plant-matter with them. That shark used to harass my Rosies badly too - was it because they ate the plants? When I feed the frozen blood worm gumdrops, he'll come take a bite or so but hardly goes into the frenzy that the rest of the tank does, preferring to go clean the tank/plants. I've tried giving him algae wafers - he doesn't even consider them a food group. He DOES however love blanched spinach leaves.

When I first put the Betta (2 weeks ago now), the shark was ok with it and would've been a good neighbor - but that darned little Betta sneaked up on him in a Myrio stand and bit him and the feud began. The shark has been in the tank for almost a year now and is quite the guy.
 

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yea, This is all interesting and may be typical. I have read a few things about betas and found that they are normally peaceful with other species.....except when it comes to good looks and nice fins. Betas tend to get aggressive toward other fish with big or bright colored tails (RED TAILED shark). Some say that betas confuse the other fish as another male betta. Another theory (The one I think is correct) is that the betta sees the other good looking fish as intimidating and potential competition, and I know bettas don't like competition. If I recall, bettas have razor sharp teeth... so if that betta wanted to do that shark in he probably could have.

Since bettas can live in smaller courters, my recommendation would have been to move the betta. So good choice!
 
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