Can you tell if a betta is going to be aggressive when you buy it?

[Leopardfire]

I'm probably going to be getting a new betta soon since my betta Comet is about to die.
Anyway I am going to be keeping my betta with corydoras, so I need to get one that will get along with other fish. Is there anyway to tell if a betta is super aggressive just by watching it in the cup? I've noticed that some bettas flare like crazy when I walk up, so does this mean they are probably aggressive?

[Bettagirl101]

How do you know that Comet is about die? I'm sure there is something you can do to save him.

[registereduser]

Mine was fine with cories it was the otos he chased.

[Leopardfire]

Originally Posted by Bettagirl101

How do you know that Comet is about die? I'm sure there is something you can do to save him.

Well I'm hoping desperately that he will make it, but he is bloated with clamped fins and he isn't moving so I don't he's going to last too much longer. I've been doing everything I could for him, but he was sickly from the start and I just don't think there's much else I can do besides wait and see if he makes it.
He is super docile though so I want to make sure that if I do have to get another betta it will be just as calm.

[Silverfang]

It it possible... I bought this one girl, because she was so lively she was trying to bite her way out of the cup she came in. But really, it's not likely to show it's aggression unless it's in a tank with another fish. (please note I am not suggestion you try this out!)

[Leopardfire]

I want to keep my tiny female with an ADF, but I'm worried she might be aggressive. She bit her net everyday when I tried to train her to go through it and she is an energetic eater. Are these signs that she could be aggressive?

[aokashi]

hard to say. I tend to think that all passive bettas in their little cups are sick bettas :P

[pittipuppylove]

Originally Posted by aokashi

hard to say. I tend to think that all passive bettas in their little cups are sick bettas :P

Agreed! lol I'm a sucker for bettas in the store who try to attack me when I gently picked up their cup. That's how I ended up bringing home three of mine

[lelei]

I wouldn't say aggressive, but wanting attention, my most recent betta, flared as soon as I picked up his cup, brought himm home, and he is sweet and gentle,.. my most aggressive betta is a rescue, VT with a viracious appetite, and loves to attack anything that moves..he is the only fish in the house my daughter refuses to feed..

[Tikibirds]

I have seen some people on here say that when they are looking for females for their soerities they will put the ones they are interested in all next to each other and see how they react. Personally, I don't think their method is very trustworthy but I guess its may be worth a shot? My method of betta picking is to pick the one that needs the most TLC but is not on deaths door.