Strange guppy

[Robinlikescories]

A friend of mine has a tank with some neon tetras, guppies and a snail. One of the guppies started to kill the tetras and the other guppies by fighting them and stopping them from feeding. It killed all but one tetra which they named slippy because he "slipped" away from the killer guppy. Then the guppy then hopped the twig too. Is it common for guppies to act like this? They got the fish in a massive fish-only pet store which is very good.

[TheSwissAquarist]

Sounds very strange, could have been a brain tumour causing irrational behaviour?

[Scapexghost]

No, this is quite unusual behavier for a guppy.

[lefty o]

that is unusual behavior out of a guppy.

[gardenman]

Sometimes healthy fish will attack and kill (or try to drive off) an unhealthy fish. It's possible that tank had something undiagnosed that was affecting the tank that the guppy detected and was trying to get rid of. It's also possible that mystery disease is what truly killed the other fish. Guppies aren't all that piranha-like in their ability to kill a healthy fish. They have tiny little mouths and while they could worry a fish, it would be challenging for them to kill an otherwise healthy fish. My suspicion would be that the guppy detected an illness in the other fish and was trying to drive them away and the other fish died of the illness, not the guppy attacks. 

[Minanora]

I've kept guppies for the better part of 20 years. I've never seen a guppy go on a murder spree. I've never owned a betta but that sounds more like betta behaviour. 

The most aberrant behaviour I've seen from a guppy was one that just wanted to mate with everything. His name was Pako and he was the Pepe Le Pew of guppies. RIP Pako.

I've never seen the behaviour that @gardenman mentioned but that is a possibility!

[Henry the fish keeper]

I keep guppies for a long time and I never saw a guppy killing one of my fish. Something is definitely wrong with your guppies.

On 4/14/2022 at 7:38 AM, gardenman said:

Sometimes healthy fish will attack and kill (or try to drive off) an unhealthy fish. It's possible that tank had something undiagnosed that was affecting the tank that the guppy detected and was trying to get rid of. It's also possible that mystery disease is what truly killed the other fish. Guppies aren't all that piranha-like in their ability to kill a healthy fish. They have tiny little mouths and while they could worry a fish, it would be challenging for them to kill an otherwise healthy fish. My suspicion would be that the guppy detected an illness in the other fish and was trying to drive them away and the other fish died of the illness, not the guppy attacks. 

I agree I had a male platy kept chasing away a female platy that had internal parasites. 

[gardenman]

Attacking a sick/weaker fish is not an uncommon behavior. You see it more in schools of fish than individuals, but you'll also see it in some individual fish. It happens. Given that the other fish died, and guppies aren't typically a killing machine, I'd say disease killed them and the guppy was just trying to keep them as far away as possible.

[Hannah Parker]

Occasionally beginners will think a betta is a guppy. I've seen the mistake before, that sounds more likely.

[Robinlikescories]

The guppy would stop any of the other fish get to the surface to feed more often than killing them directly.

On 4/14/2022 at 4:27 PM, gardenman said:

Attacking a sick/weaker fish is not an uncommon behavior. You see it more in schools of fish than individuals, but you'll also see it in some individual fish. It happens. Given that the other fish died, and guppies aren't typically a killing machine, I'd say disease killed them and the guppy was just trying to keep them as far away as possible.

No. The tippy would stop them from eating by not letting any fish get to the surface,beating them up and stealing food from other fish

[sumplkrum]

I feel like 'Evil Guppy' should be a brand for something. 🤔