Who’s Killing My Corys?

I’ve got a 75 gallon fully cycled freshwater tank. Parameters are all good and steady. Inhabitants are (or were) 8 albino corys, 15 rummys, 3 blue dwarf gouramis, and 2 juvenile angels.

For the past two weeks, the day after fast day I noticed a mostly eaten cory on the bottom. At first I thought one just died and after the second week in a row I assumed someone was getting hungry, and killing and eating a cory so I abandoned fasting.

I forgot to feed the fish yesterday. Today, lo and behold I’ve found another half eaten cory cat. I haven’t seen any signs of aggression in the tank, and I would think the the rummys would be a more likely meal for a hungry fish due to their smaller size and the fact they don’t school as tightly since the inhabitants are all relatively calm.

The only thing that’s really changed recently is the size of the angels, so they are my most likely culprit, although I am surprised they aren’t going after the tetras...

Any other thoughts? Thanks!

 

Species of Cory? Water temp? How long have the cories been in there? What/how often are you feeding?

 

Well, it's also possible that they're dying from other reason and the other fish are just helping themselves to some food. We don't know enough about your fish and aquarium to really be able to tell. Besides potentially the angels, I'm pretty sure your stocking wouldn't bother them to the point of death. But I do know cories can be sensitive to parameters and other things.

It is rather interesting that both deaths occured after fasting, though. So perhaps your fish are hungry, maybe the young angels.

 

My biggest concern with that kind of setup would be; is enough food making it down to the cories. You have some pretty aggressive feeders in there; so it’s a possibility that there isn’t enough food getting to the bottom

 

Water temp is 78. Corys are albino. Parameters are all good. Always 0 on ammonia and nitrite. Nitrates hit about 40 before water changes. They were the first fish I added after a fishless cycle about 6 months ago. I’m feeding the angels and gouramis either freeze dried blood worms, or omega one flakes, HikarI micro pellets for the rummys, and shrimp pellets for the corys.

Now that I think about it, I have noticed the gouramis in particular going after the shrimp pellets. I suppose it is possible that the Corys aren’t getting enough to eat, starving to death, and getting eaten. That makes me sad.

Lately I’ve been feeding extra micro pellets to make sure some gets down to the bottom for them... Perhaps I need to feed them after dark?

 

my cories are daytime feeders. They scent it in water & come swimming. I add 1 pellet per kitty cat at exact same area - on top of a magnolia leaf that was added to tanks for tannins. the leaf is surrounded by plants near a corner. Granted, I've only had them almost a month, but they are doing very well. Plus, I add algae tablet each day.

the 2 I lost were due to fish aggression with tails bit off.

do they have enough areas to retreat? I have a bridge, house, tree structure, 6 plants in front glass pane with 2 pieces of driftwood ( 1 at each end also with plants), so the exposed area they swim is maybe 4 inches max per front. Helps prevent Skirt tetras zoning in on them for the chase.

 

I have never heard of any fish going after Cory’s. I always though mostly because of the barbs. I don’t see any fish in your tank that would attack a Cory. This is a strange one for sure.

 

Water temp is 78. Corys are albino. Parameters are all good. Always 0 on ammonia and nitrite. Nitrates hit about 40 before water changes. They were the first fish I added after a fishless cycle about 6 months ago. I’m feeding the angels and gouramis either freeze dried blood worms, or omega one flakes, HikarI micro pellets for the rummys, and shrimp pellets for the corys.

Now that I think about it, I have noticed the gouramis in particular going after the shrimp pellets. I suppose it is possible that the Corys aren’t getting enough to eat, starving to death, and getting eaten. That makes me sad.

Lately I’ve been feeding extra micro pellets to make sure some gets down to the bottom for them... Perhaps I need to feed them after dark?

Just a thought but 40ppm nitrates might b a bit high for the corys as these guys r really sensitive to ammonia nitrites and nitrates than other fish