How do I know if my fish died or was killed?

[bostonbass]

Hi all. I woke up this morning to a dead Zebra Danio. He had been chewed up pretty bad but that was probably the catfish. How do I know if I have a ruthless murderer in my tank or if the Danio just swam into the wall too fast?

20 gallon high planted
water quality is good
10 zebra danios
2 bumblebee catfish
1 rainbow shark fish
1 black molly
3 oto cats
4 assassin snails
5 amano shrimp

 

[lksdrinker]

Hi all. I woke up this morning to a dead Zebra Danio. He had been chewed up pretty bad but that was probably the catfish. How do I know if I have a ruthless murderer in my tank or if the Danio just swam into the wall too fast?

20 gallon high planted
water quality is good
10 zebra danios
2 bumblebee catfish
1 rainbow shark fish
1 black molly
3 oto cats
4 assassin snails
5 amano shrimp

I cant think of a good way to know. Especially if the dead fish has already been pecked at by the other tank inhabitants. I suppose you could put the fish under a microscope and check the gill area for parasites.

 

[bostonbass]

I cant think of a good way to know. Especially if the dead fish has already been pecked at by the other tank inhabitants. I suppose you could put the fish under a microscope and check the gill area for parasites.

I actually think it might be the Molly. He was originally in a smaller tank and his first day he killed a Cardinal Tetra. Now the Danio in the larger tank. What would turn a Molly, considered a community fish, into such a jerk?

 

[lksdrinker]

I actually think it might be the Molly. He was originally in a smaller tank and his first day he killed a Cardinal Tetra. Now the Danio in the larger tank. What would turn a Molly, considered a community fish, into such a jerk?

Fish are just like people. Some are just jerks for no good reason!

 

[Cecibella123]

Some fish become more aggressive when they're the only fish of the species in a tank. Never known mollies to be that aggressive though, but there's always a first time. If I'm not mistaken (which I am, all too often), danios hover at mid water when lights are off, so it's unlikely the catfish killed it. They're also very fast, so if the molly did indeed kill it, and you still want to keep the molly, just make sure there are hiding areas that the danios can escape to when threatened.

 

[bostonbass]

Some fish become more aggressive when they're the only fish of the species in a tank. Never known mollies to be that aggressive though, but there's always a first time. If I'm not mistaken (which I am, all too often), danios hover at mid water when lights are off, so it's unlikely the catfish killed it. They're also very fast, so if the molly did indeed kill it, and you still want to keep the molly, just make sure there are hiding areas that the danios can escape to when threatened.

There was one danio that kept to the surface ever since I added them to the tank. The rest schooled up mid-level. Maybe that one just wasn't right.

 

[PB_Smith]

molly's can be very aggressive, especially the black ones or any strains derived from them.


BUT you also have a rainbow shark in there. All those sharks are very aggressive and will quickly outgrow a 20 gallon tall tank. They need lots of back and forth swimming room.


Personally in that size tank I would consider something else instead of the molly and shark.

 

[Cecibella123]

It's possible that it died of "natural" causes. The catfish would likely try to eat an easy meal lying on the bottom.

 

[bostonbass]

molly's can be very aggressive, especially the black ones or any strains derived from them.


BUT you also have a rainbow shark in there. All those sharks are very aggressive and will quickly outgrow a 20 gallon tall tank. They need lots of back and forth swimming room.


Personally in that size tank I would consider something else instead of the molly and shark.

The shark has actually been quite happy, even cohabitating with one of the bumblebees. But if he gets too big for the tank, I'll either get a bigger tank or sell him back to the store. Also, Rainbow Sharks are classified as semi-aggressive and the one I have hasn't gone after a single fish.