CPDs cannibalizing???

[lilsd]

I’ve heard that CPDs will eat their own eggs and fry, but never heard of them going after adults?? Mine have been living together peacefully for several months now, I see them chase each other around from time to time but always thought that was just part of their normal behavior. Today I noticed one swimming kind of odd and crooked, and looking closer he’s got a couple large chunks taken out of one side of his body. 1-2 others were nipping and harassing him. Water parameters are normal and nothing has changed in the tank for months. Is this something they are known to do? Did I do something wrong? I don’t think there’s anything I can do to save him at this point… the tank is densely planted and I think I’d cause more harm than good trying to catch and separate him, he’s hiding now but I don’t think he’s going to live long…. Poor guy. I’m a newbie and just want to know if I did something wrong or if this is just a freak thing that can happen??

 

[EmmaS]

I've kept these species for over 3 years now and they can get fiesta with each other but not to the extent of injuries. Maybe a nipped fin. It's mainly with the males. I have heard before they can be aggressive . I can only go on my experience and they are no worse than any other fish.
Be interesting to hear your setup ie tank size and inhabitants.

 

[lilsd]

It’s a 10gal tank with 5 CPDs (about to be 4…) a dozen or so chili rasboras and a few neo shrimp. Lots of plants and natural hiding spots. This is the first time I’ve seen something like this.

 

[seangee]

Mine used to regularly take chunks out of each other. I had lots of plants in the tank and plenty floating as well. Usually when one got beaten up badly he (it was always the hims ) would go and hide out in the floating plant roots for a few days to recover. I did have some casualties, but very few compared to the number of injuries.

 

[EmmaS]

It’s a 10gal tank with 5 CPDs (about to be 4…) a dozen or so chili rasboras and a few neo shrimp. Lots of plants and natural hiding spots. This is the first time I’ve seen something like this.

I have about 20 so maybe why I don't get this problem. The only time I have them in a small group like yours is when I breed them.
What sex are they ? Try breeding them it's extremely easy. You are probably at your limit to be fair.

 

[lilsd]

I do realize I am probably at the upper limit for stocking density, but everything has seemed peaceful so far as I can tell up until now. I have a hard time telling the males and females apart so I’m not sure on that one. The one who was attacked was one of the larger ones so I’m guessing a male?

 

[gwand]

I have 10 CPDs in a well planted 10 gallon tank for about 3 years. I have seen males chasing each other but I haven’t seen any injuries. I have never seen fry so maybe they are eating eggs and/or fry.

 

[GaryE]

I doubt it's directly cannibalism, but it could be murder.

What temperature are they at?

 

[lilsd]

Temp sits between 75-76F

 

[EmmaS]

Can you take a few pictures and I'll try to sex them.

You can also drop the temperature down to 72f comfortably. This will also benefit your shrimp greatly and your electric bill lol.

 

[MaloK]

What is your feeding schedule and how much do you give ?

 

[seangee]

It’s a 10gal tank with 5 CPDs (about to be 4…) a dozen or so chili rasboras and a few neo shrimp. Lots of plants and natural hiding spots. This is the first time I’ve seen something like this.

Ah - I did have 20ish in a 15G. I'd still be inclined to up their numbers to 10 or 12 which will spread the aggro. I always said the minimum should be 20. As you have lots of plants and its a mature system they will be fine as long as you do regular water changes. I'd be far more concerned about the chilis in that size tank with their habit of racing around , but as they are there and doing OK its no harm done.

 

[GaryE]

I asked about temperature because that can affect aggression. Their range is 20-26c, so 68 to 79f. If you bring it down to 71/73f, you may solve your issue. Maybe. It often works, but I never kept that species above 22c/72f. I also never saw any violence with the ones I babysat for a few months.

They bred at the temps I had them in, so they seemed happy.

 

[lilsd]

My heater isn’t adjustable but I can look into getting one that is. I’ll try to take some pics tomorrow, but it seems like the fewer they are the more elusive they are… they’re definitely a lot more shy than the chili rasboras, and tend to hang in the plants a lot of the time. Maybe getting a few more would help I’m not sure. But I know I’m walking a fine line with overstocking too…

I have cut back a little on food the past couple weeks since I’ve been battling issues with algae and surface biofilm. I’m not sure if that’s part of the issue. I feed them once a day, 6 days a week. I skip feeding on Sundays but I feel like there is lots of natural stuff in the tank for them to scavenge… most days they get flake food but once a week or so I give them frozen brine shrimp.

 

[GaryE]

You have an interesting possibility there. Bororas brigittae, the chili rasbora, has a 20-28 temperature range. What would you get if you went with no heater? What are room temps like in your house?

I had a group of the related Bororas maculatus that actually bred quite a bit in a softwater tank at a room temperature of 21-22. So the CPDs are known to like the cooler side of their range, and the Bororas don't mind. I've never kept shrimp to know though.

There's no guarantee it would solve the fighting. But going for the lower safe range with a number of small fish has dialed down aggression here. The fish often live longer too.