Smaller Fish Disappearing, What Could Be Responsible?

[marieukxx]

My sister has a 125L tank. This past week every one of her cardinal tetras has disappeared one by one and now today the smallest female betta she had in there has disappeared.

She has a female betta sorority in there, danios, and one rainbow fish. She did have two rainbows but one kept picking on the other and it died. She's thinking it could be the rainbow that's responsible.

She can't remember what type the rainbow is but it looks like this:
http/www.fishdeals.com/misc/rainbowfish/

The guy in the shop told her it was a peaceful community fish.

Forgot to say, the tank is established, all tests are fine

 

[Iiriva]

Does the so called rainbow fish have totally silver body or is it a bit yellowish from back end?

 

[marieukxx]

Bit yellow on the back end

 

[Crossfire]

Have you checked the filter? Maybe they're getting sucked in.

 

[marieukxx]

Have you checked the filter? Maybe they're getting sucked in.

Thanks, she's checked that and also the filter is in a box inside the tank along with the heater

 

[Crossfire]

Have you looked around the surrounding areas of the tank? Behind it? Maybe they all jumped ship. If not, then I have no idea

 

[marieukxx]

First to go was the other rainbow, she noticed a lot of fisghting between them, then one by one the cardinal tetras and now the smallest betta

 

[Prime Ordeal]

Is the rainbow fish quite large compared to the missing fish?

 

[marieukxx]

yes it is a lot bigger

 

[Prime Ordeal]

Well there's your answer then. Boesemani rainbows will eat fish if they're small enough.

 

[marieukxx]

thought it was the rainbow. Thanks

 

[N0body Of The Goat]

Rainbowfish have very small throats for the size of their body, food needs to be very small size, so I very much doubt the Bosemani Rainbowfish is treating the Cardinal Tetra as live lunch. But in any case, Bosemani Rainbowfish should be in schools with at least two females to every male and given their typical ~10cm size as aquarium adults plus their activity, a generous sized 4-foot tank (240l) is their minimum requirements.

Bettas can sometimes get nasty with other colourful fish in their area. Danios, if kept in small numbers (<6), can become spiteful too. Most prefer strong currents, a complete constrast to Betta splendens. While neither could swallow anything but a young Cardinal fry whole, they could harrass them, inflicting death causing injuries and then the corpses are nibbled at by all occupants.

 

[Prime Ordeal]

I very much doubt the Bosemani Rainbowfish is treating the Cardinal Tetra as live lunch.

The proof of the pudding is in the eating! (pun intended).

 

[N0body Of The Goat]

That's some photo, Prime Ordeal, was the Cardinal definitely still alive? Did the Bosemani sucessfully swallow it too without consequence in one piece?

 

[Prime Ordeal]

It's not one of my photos, I half inched it from another site. But yes, the tetra was alive and well when taken and was eaten whole!