# Betta fish has killed Harlequin rasbora



## Birdman99 (Jan 1, 2021)

just got up to find that my male king Betta has killed one of the Harlequin rasbora.
Not a pretty sight.
I read loads of research to say that Betta fish were ok with these fish as long as there in shoals.
What has gone wrong?
has anyone known of this?


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## Moo Moo (Oct 29, 2020)

How big is your tank?
Has he been chasing the other fish lately?
What is his personality like,is he normally aggressive?
Maybe the rasbora got in his way?idk


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## Hania41806 (Dec 10, 2020)

There are a lot of reasons bettas can get aggresive. You should probably separate the rest of the tank mates (if there are any). Could you show us a picture of the tank?


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## Keenamoss (Aug 21, 2020)

My betta was peaceful as anything with 5 rasboras and a bristlenose in his 130L planted tank, but I think it was when I added 3 kuhli loaches, suddenly he started chasing not only the kuhlis but also going after the rasboras really aggressively all day, so I had to set him up on his own. Felt pretty guilty, it seemed to me I just pushed his limit as to how many things he felt he could share a space with. It also occurred to me that maybe, he had matured by then too as I hear that young ones can be OK but sometimes turn as when they become sexually mature they can be more territorial. I also thought I had plenty of plant cover but looking back, it wasn't really as dense as I thought, these days it's literally a jungle. He's also still managing some health issues he seems to have been born with, my other betta from the same supplier also has strange mystery illness though different symptoms, receiving ongoing treatment, and if an animal is injured or stressed this could make them more aggressive? Or maybe it was a combination of these factors, no one can really say for sure in this fish game. I'm sorry it hasn't worked out  have you got a plan B set-up for him?


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## Birdman99 (Jan 1, 2021)

Hi guys thanks for your responses and help he is in a 10l tank.
I often seen him chasing the rasbora but thought he was just showing them who was boss, not for a minute did I expect to wake up and find a tiny carcass, he had eaten almost the whole fish by the time I woke so must have been on it all during the night .
I have had Betta before but Luca is very grumpy and has a funny personality. If you put you finger in he will bite it 😂
I have remove the rest of the rasbora so he will be on his own which is sad because my thinking was if he had other fish to live with it would keep him from getting bored.
Maybe if I had a bigger tank this wouldn’t have happened .


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## RussellTheShihTzu (Mar 19, 2013)

Is 10l 2-3 gallons?


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## Hania41806 (Dec 10, 2020)

Birdman99 said:


> Hi guys thanks for your responses and help he is in a 10l tank.
> I often seen him chasing the rasbora but thought he was just showing them who was boss, not for a minute did I expect to wake up and find a tiny carcass, he had eaten almost the whole fish by the time I woke so must have been on it all during the night .
> I have had Betta before but Luca is very grumpy and has a funny personality. If you put you finger in he will bite it 😂
> I have remove the rest of the rasbora so he will be on his own which is sad because my thinking was if he had other fish to live with it would keep him from getting bored.
> Maybe if I had a bigger tank this wouldn’t have happened .


 That's quite a bit too small. 10l (Which i'm guessing is liters) Is about 2.6 gallons. A betta that has tank mates should probably be in a 5 gallon or more (about 19 liters or more). He was probably being territorial over the little space he was left with.


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## Hania41806 (Dec 10, 2020)

Hania41806 said:


> That's quite a bit too small. 10l (Which i'm guessing is liters) Is about 2.6 gallons. A betta that has tank mates should probably be in a 5 gallon or more (about 19 liters or more). He was probably being territorial over the little space he was left with.


to be clear, a 10l tank is perfect for just one betta, and your fish is probably happier in that than most pet bettas.


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## Birdman99 (Jan 1, 2021)

RussellTheShihTzu said:


> Is 10l 2-3 gallons?


That correct


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## RussellTheShihTzu (Mar 19, 2013)

Birdman99 said:


> That correct


Thank you. Even when I look it up I'm never really sure.

If you check any shoaling fish species profile you will find Nano fish under one inch require a 24" long aquarium; Nanos over 1" need a 30" length. I realize everyone goes by gallons but that's not really an appropriate way to determine what can go where. Because of the needs of the shoalers, they should never be kept with a Betta in anything but a 24"-30" well-planted tank. And while most Betta can do well in a 2.5/10l, King and Giant Betta need a minimum of a 24" long aquarium. 

FWIW, in all the years I've had Betta, I've never actually seen one catch and kill _healthy_ fish or shrimp. Although I can understand that might be possible in an overcrowded tank or a predator has a straight line with no plant or decor obstacles. Betta are opportunistic feeders; if something is dead or dying they'll make a meal of it.


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## MaGiC74 (Aug 17, 2020)

Birdman99 said:


> just got up to find that my male king Betta has killed one of the Harlequin rasbora.
> Not a pretty sight.
> I read loads of research to say that Betta fish were ok with these fish as long as there in shoals.
> What has gone wrong?
> ...


The information on the web is probably just in general. Individual bettas all have different personalities and perhaps he is more aggressive. Just make sure you have a big enough tank with a lot of plants


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## GMWNMW (Jun 19, 2014)

Unfortunately, male bettas are extremely unpredictable creatures. Once you think you have them figured out (concerning cohabiting with other types of fish) they will prove you wrong. Sorry for your loss.


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