Do Fish Kill And Eat Other Fish?

[Aquapotts]

I have had a biorb tank setup going for a couple of months now. It has passed through the cycle phase with a few hiccups along the way and up until last week I have only had guppies in there (four guppies to be precise). Last week I decided to add 4 harlequin rasbora and they all seemed to be doing well, and the water conditions did not change as I am still doing daily tests to keep an eye on things.

I was told that the harlequins and guppies are all quite passive and so should get along fine, however I have come home today to find I am now one harlequin missing. I have searched the whole tank, removed ornaments and checked through the live plants, studied the ceramic media, everything and I can't find him - it has now been several hours and I am sure that he is not there.

Is it possible he may have been "bullied" and killed and eaten? None of the fish have been displaying any symptoms of illness and I have been studying there behaviours very carefully.

I am now concerned that the remaining fish will not get along and will become agressive to each other. I have 4 guppies and now 3 harlequins... please help...

 

[WILDER]

How many gallons is the biorb.

I kept harlequins and guppys together and never had any problems.

Do you have any pets.
Make sure he hasn't gotton out of the tank. So check around the tank area and floor.
Check inside the filter.

 

[Aquapotts]

Thanks for your reply, it's a 60 litre biorb (is that 16 gallons?!?!) There is no way the fish can get out because of the bowl type shape, plus it has a good fitting lid on it 24/7. Is it possible that having only 4 harlequins has caused a problem with dominance/bullying in the tank?

 

[WILDER]

Its best to keep at least 6 harlequins.
I have never had any problems with harlequins bullying. They always seem to get along.


Only thing I could suggest is removing plants and ornaments from tank.
If the fish dosn't show up it sounds like the other fish have eaten it.

 

[Aquapotts]

Thanks. He's defintely not in there unless he somehow got under the ceramic media. It does seem very unusual. I am a little concerned for my remaining fish, but not sure if I should do anything...

 

[WILDER]

I once found a dead fish wedged between the media so I would remove it to make sure.

 

[Aquapotts]

Thanks, I'll keep searching. Do you mind if I ask you some more questions...? What do you have in with your Harlequins? How do different types of fish interact? My Harlequins seem to just be staying out of the guppies ways and every now and then the guppies will dart towards them - do you think this is just fish being playful or do you think the guppies don't like the new Harlequins?

 

[GuppyGoddess]

Thanks, I'll keep searching. Do you mind if I ask you some more questions...? What do you have in with your Harlequins? How do different types of fish interact? My Harlequins seem to just be staying out of the guppies ways and every now and then the guppies will dart towards them - do you think this is just fish being playful or do you think the guppies don't like the new Harlequins?

Hi,

Do you have a flashlight? If you shine it around in your tank, you may be able to see the reflection from the fish's eyes. Earlier one of my pygmy cories was hiding and I found him that way.

That aside, in a seperate tank, I have three rasboras with a female betta and the rasboras are entirely passive. They swim around and do not even attack each other or do anything but swim with their group.

ETA - if the guppies are darting toward them, they may not like them. I put the above mentioned cories in with my guppies and the guppies ignore them. The guppies just dart at each other. They kind of bicker!

Hope all works out well for your fish.

 

[kelly528]

Do you have a flashlight? If you shine it around in your tank, you may be able to see the reflection from the fish's eyes. Earlier one of my pygmy cories was hiding and I found him that way.

Whoa thats a good one--- do you do it with the tank/room lights off or on?

 

[GuppyGoddess]

Do you have a flashlight? If you shine it around in your tank, you may be able to see the reflection from the fish's eyes. Earlier one of my pygmy cories was hiding and I found him that way.

Whoa thats a good one--- do you do it with the tank/room lights off or on?

The only time I've had to try this was today. . .it was around 8 AM so the kitchen lights were on as was the tank light. Since the fish was hiding in a "cave" of sorts, he was easy to spot in the dark. With that said, if your tank doesn't have many dark hiding spots, it may be better to try with the lights off so you gain the same effect.

 

[WILDER]

Have you managed to find him yet.

Black neons get on with harlequins well. They shoal together.

 

[austin2.0]

Some aquarium bubbler decorations (the kind with a built in bubbler) have a hole in the side for the air hose that is large enough for a guppy to squeeze in as well. I had a guppy do this and perish inside. I thought he had simply been eaten (he was the smallest fish in the tank) but in fact I found him dead, and hidden inside when I took out the whole bubbler decoration.

 

[Aquapotts]

Thanks to everyone for you advise and concern for my fish...

Unfortunately, there is still no sign of the missing Harlequin! The biorb bubbler and filter are all connected as part of the tank so there are no small parts of holes for the fish to get in. I suppose it may be possible that he swam down the bubble tube, in which case he'll be with the filter sponge at the bottom of the tank. More likely he has tried to get beneath the ceramic media for some reason and got stuck, but I've moved some of the bigger bits around and there is no sign of him. I'm totally baffled! Will check the filter on the weekend, but keeping an eye on the ammonia levels until then...