Tetra behavior

[J. Holmes]

Are all tetras aggressive? I have two community tanks each with a betta. One is a 40 and the other a 20. I have half moon bettas in them with endlers, snails, shrimp, and Ottos. The other fish I have are Cardinal tetras. I did research before setting up my tank thinking they would be peaceful fish to give my tank a pop of blue. But these are AGGRESSIVE! They torment my poor bettas and other fish. They chase them around the whole tank nipping their fins, pushing them out of plant cover. My poor bettas have both taken to hiding in holes and it’s a struggle to encourage them out to even feed. I’m going to rehome these guys, but I’m curious if this is normal behavior for all tetras? If I got some neon tetras, would they be kind to everyone? 

Edited January 4, 2023 by J. Holmes

[FLFishChik]

I  have a 29g with Cardinal Tetra, otos, Cory’s and Nerites. I did have a Betta at one time and did find the Cardinals could get a bit fin-nippy when it came to feeding time.

[Rube_Goldfish]

How big is your school of cardinals? I have a school of twenty in a 55 gallon community tank with sterbai cories, honey gouramis, and otos, and they just sort of laze about all day (unless I startle them and they dart from one end of the tank to the other). But I've heard that tiger barbs can be aggressive when the shoal is too small and they act out of fear; maybe tetras are the same?

[J. Holmes]

On 1/4/2023 at 4:05 PM, Rube_Goldfish said:

How big is your school of cardinals? I have a school of twenty in a 55 gallon community tank with sterbai cories, honey gouramis, and otos, and they just sort of laze about all day (unless I startle them and they dart from one end of the tank to the other). But I've heard that tiger barbs can be aggressive when the shoal is too small and they act out of fear; maybe tetras are the same?

I’ve heard that as well. I got a school of 8 for both tanks. They are both just extremely aggressive from the beginning. 

[Theplatymaster]

can you provide a picture of these tetras?

[J. Holmes]

On 1/4/2023 at 4:09 PM, Theplatymaster said:

can you provide a picture of these tetras?

[JMP]

There are definitely different levels of aggressive behavior with Tetras. I have 22 Neons in a 75 gallon with several Albino Cory and a Butterfly Pleco that turned out to be a Godzilla Pleco (NOT a butterfly). The Neons get a bit nippy with each other at times. I’ve had Cardinals in the past and they can be nippy and definitely would be aggressive toward big plumed fish fins. Even with a school of Tetras there is a pecking order that can develop.

Is it possible to move all the Cardinals into the larger tank? If this is possible then additionally I’d rearrange the tank to disrupt any territories the Cardinals currently in the tank have developed. Adding all the Cardinals together may direct their aggressive behavior toward each other and off the Betta. Unfortunately you may be faced with separating the Betta from the Tetras or trade them in for a more peaceful species of Tetra. Good luck.

[J. Holmes]

On 1/4/2023 at 5:49 PM, JMP said:

There are definitely different levels of aggressive behavior with Tetras. I have 22 Neons in a 75 gallon with several Albino Cory and a Butterfly Pleco that turned out to be a Godzilla Pleco (NOT a butterfly). The Neons get a bit nippy with each other at times. I’ve had Cardinals in the past and they can be nippy and definitely would be aggressive toward big plumed fish fins. Even with a school of Tetras there is a pecking order that can develop.

Is it possible to move all the Cardinals into the larger tank? If this is possible then additionally I’d rearrange the tank to disrupt any territories the Cardinals currently in the tank have developed. Adding all the Cardinals together may direct their aggressive behavior toward each other and off the Betta. Unfortunately you may be faced with separating the Betta from the Tetras or trade them in for a more peaceful species of Tetra. Good luck.

Gotcha… yea I’ve tried multiple different locations for these guys. They’re just rude! What are the more “peaceful” type of tetra? I would love that blue in my tank with my betta boys 

[Ninjoma]

I had black skirt tetras for a while. They nipped and chased each other a decent bit, sometimes causing fin damage. They also atr all my mystery snail antennas. 

They coexisted peacefully in my 40g with zebra danios, corys, hillstream loach, and fancy goldfish. They also coexisted peacefully in my 29g with an angelfish, khuli loaches and honey gourami. I did notice my khulis were more active when I removed the tetras though. 

I also have neon tetras in my 10g with shrimp and snails and I haven't noticed any agressrion from them. 

[JMP]

On 1/4/2023 at 4:51 PM, J. Holmes said:

Gotcha… yea I’ve tried multiple different locations for these guys. They’re just rude! What are the more “peaceful” type of tetra? I would love that blue in my tank with my betta boys 

Unfortunately most of the Tetras can be aggressive depending on their tank mates and environment. Multiple males in a school can lead to aggressive behavior toward each other and other tank mates. Especially fish with fins like Betta. You could try Neon Tetra as they typically only nip at each other. The Emperor Tetra are normally peaceful. Those two are the only ones I could recommend. A heavily planted tank could help make the fish more relaxed and less likely to be aggressive toward other tank mates. Unfortunately the big frilly fins of the Betta are really tempting for fish that normally don’t nip.

[Janoš Bećar Pecaroš]

I have a school of glow light tetras with one of my bettas and I did not notice any aggressive behavior from tetras towards the betta. Sometimes, the tetras would chase each other.

But, they aren’t blue at all.