I have had a betta for over 4 months now in a 2.5 g tank.I also have another 16 g tank where there are 2 buenos aries tetras,3 daniels,1 goldfish,1 male guppy,2 killis,and 2 sharks(bala).my betta seems very lonely and bored.please help..can I put betta in the bigger tank with all the other fish??
Leave the betta in it's own tank. Try putting a mirror or something up by his tank so he can flare at his reflection for a little bit. Maybe that will cure his boredom.
In your other tank, you should think about taking back the goldfish. They're coldwater fish and should be kept in larger aquariums b/c of the potential size they get and b/c they're heavy waste producers... or something like that heh.. I'm sure someone else more knowledgeable will be able to tell ya about that.
bala sharks also get too big for a 16 gallon... nearly 11 inches if I'm not mistaken. Sorry!
About your question though, bettas can sometimes be okay with a otto cat or a cory cat... You would need to have a larger tank though. Maybe two ottos and one betta in a 5 gallon tank???
thnakyou all for the great ideas...as far as the goldfish...he was my first fish ever ..he was initially about 1/2 inch(feeder fish , 5 months ago))....now he is about 5 cm(2 1/2 inches) and he seems healthy and happy..I wasn't aware that he is not supposed to be with the tropical fish...temperature stays at 80...I know..I got to get a bigger tank...and maybe leave the betta in the one that I already have...but still don't know what to do with the goldfish since he would need a new tank alltogether for himself...and he is my favorite so I don't want to give him away...iris
One problem is that the Tropical fish will be getting sick when kept with a goldfish as the goldfish are terribly dirty fish (meaning that they put out a LOT of waste) and the Tropicals just cannot handle it. You will need to be doing very frequent gravel vacuuming and water changes to keep the fish healthy.
The betta is used to being alone and has been since a very short time after his birth, he is bored because he has not got enough room to explore and do anything in. If you put more fish in there with him it will just make it worse as he will feel even more cramped. I am sorry but the main thing you can do for him is to get him a bigger house. Then if you want to get him a couple of friends get a couple of Otocinclus catfish for a 5 gallon tank or if the tank is larger you could get Otos, Cories, or Dwarf Loaches. They all get along well with Bettas but need to be in groups of more than one.
How is it going with your Betta? Is he in the 2.5g or moved to a new, bigger tank? Does he have something in his tank to swim through & around like a rock formation with holes big enough for him (and no rough edges)? That and a live plant or 2 might fit in the 2.5g and give him some entertainment, but the other replies are right - our Bettas are perfectly happy by themselves in a 10 gallon tank but get along great with otos, corys & loaches like chickadee recommended.. just make sure your little Betta doesn't gorge himself on their food - some Bettas like the food for those fish & some wouldn't touch the stuff. Talking to him some and a mirror for a few minutes a day are also good ideas.
If you have the room, check around for those aquarium kits.. like the 5 gallon hex (good if space is at a premium) or 10 gallon rectangular.