Chromis is behaving strangely

[storm9]

I've got 6 blue/green chromis in my tank and they were all doing great yesterday, eating and acting normal. But today, one of them is just sitting in the corner, hardly moving. He looks fine, except for a tiny cut on his dorsal fin, but I don't think that's the issue. He's trying to eat, but can't seem to get it together - he'll take a bite, but always miss. And now he's getting aggressive with the other chromis when they come near. Water params are looking good, though - NO3 is 0, calc is 425, pH is 8.2, and alk is 10. Haven't tested for mag in a bit, but I can if you want.

[rustix]

I'd want to see the rest of your water stats, like ammonia, salinity, and nitrite levels. Maybe the other chromis are stressing him out, is he smaller than the rest? When you say he's missing food, does he actually miss it or is he just spitting it out? I've never seen a fish have trouble eating like that before. Post that picture when you can, and just keep an eye on him for now.

[felinxo]

Chromis are notorious for bullying the weakest link, sadly that's just their nature. Feeding them multiple times a day is key to keeping aggression in check, but let's be real, who wants that hassle?

[storm9]

I'd want to see the rest of your water stats, like ammonia, salinity, and nitrite levels. Maybe the other chromis are stressing him out, is he smaller than the rest? When you say he's missing food, does he actually miss it or is he just spitting it out? I've never seen a fish have trouble eating like that before. Post that picture when you can, and just keep an eye on him for now.

SG is 1.025. I haven't tested for ammonia or nitrite since I figure if I had either, my corals and other fish would be showing signs of stress. Initially, I thought he might be getting bullied, but he's actually the largest and does the bullying when others enter his corner - kind of like his clownfish cousins.

felinxo said:
I'm afraid chromis are well known for picking on the weakest of the group until they die they have to be fed several times a day (which most of us don't want to do) to keep this aggression at bay
Seffie x

Actually, he's the one doing the bullying...I usually feed them twice a day.

Update: He's become much less aggressive towards the others, and I can tell he wants to follow them. He does start to, but then turns around and heads back. He can catch food now too. Today, while I was cleaning the glass, I startled him, and he followed the group for a bit. But once I was done, he went back to his corner. I'm starting to think he's just not very smart.

[rileyon]

I've found that to keep a group of chromis thriving in the long run, you need a decent number - I'm talking more than four. This way, the aggression is spread out and doesn't all fall on one poor guy.

It's also worth noting that feeding them little and often, like 4-5 times a day, keeps them constantly nibbling on something, which seems to help keep the peace.

[Voyager2]

I've had a similar experience with my chromis, I started with 6 and now I'm down to one big guy. It seems like they just pick on the weakest link until it's gone. I'm in a 75G tank, but I'm not sure that size was the issue. I think it's just their nature. I've come to realize that there's not much you can do to stop it, it's just how they are.