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Recently aggressive CPD female (killed cherry shrimp)

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Hello all,

So about a week ago I noticed a couple of my female CPDs were very plump, 1 of them in particular was noticeably bigger and bulkier than the others. In the last few days, I also began to notice that she was particularly aggressive to the other cpds even the males especially in a particular corner of the tank. This was the corner where I would usually feed them and they would always gather here when I appear, never had any aggressive issues for the past 7-8 months I've had them. I was actually gonna make a post for help IDing the sex of that particular fish as I was starting to doubt whether it was a female as I had observed it engaged in a flare-off/circling with males, also it is a quite colourful female as bright as the males (usually the females are not). But it does have the black dot behind its anal fin and its body shape is very much like a gravid female CPD, so I am pretty sure its a female.

Anyways cut to a few minutes ago, I was filming the female chasing off males from this corner of the tank and just as I stopped filming, a Red Cherry Shrimp swam by and the female immediately did a 180 and nipped it. The shrimp seem to get away but I noticed it wasn't swimming very well, it trying to swim up but just floated back down. When this happened, a male CPD also took a nip then they all came and killed the poor shrimp...

I've kept the CPDs with shrimp the entire time I've had them and never seen any aggression towards them, not even dead shrimp (only other shrimp would eat them). Although, I've only had the RCS in there for about 2 weeks It seemed this attack was triggered by the female taking that first bite. As they were consuming it, I saw that other shrimp that were swimming were starting to get nipped at too (perhaps being mistaken for the dead one) so I took the body out because I didn't want them getting any ideas. Nevertheless, it seems that shrimp that come by that area is chased off by the female, she doesn't pursue them far. I think the unfortunate shrimp was just unlucky, as I know a few of them molted this morning so it must've been one of those.

I keep these guys in a 10 gallon, heavily planted tank. There's about 9 CPDs and 13 shrimp.

Anyone had any experience with aggressive female CPDs? Do gravid CPD (or fish in general) exhibit aggression? They've been breeding constantly in the tank and the last couple of days I started making actual effort into harvesting their eggs and breeding them.

I've read about aggressive male cpds but never females and also that they will eat baby shrimp. Interestingly, the females aggression only seems to be limited to chasing. They all have beautiful fins with no sign of tearing or nips.

Sorry for the long post haha, here are pictures of her.


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Premium Member
5,705 Posts
Breeding and maturity changes behaviors in fish. Most fish from LFS are juveniles and not yet developed enough for breeding. This can explain why the fish were peaceful at one point and this dynamic has now changed.
It is not unusual that the female is on high defense against the males in aquarium. She is not yet ready to pair off and breed. This aggressiveness is normal.

It also is not unusual for fish to "discover" that shrimp are a food source. There is always a risk putting fish and shrimp together.

142 Posts
Discussion Starter · #3 ·
Yeah, I knew the risk is always there but it seems that what happened was an unlucky instance as for the last couple of days the shrimp have been grazing beside her in that corner and she and the others seem to ignore them. Hopefully, none of them accidentally get in her way again!
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