Mysterious clownfish damage overnight

[plantscoralsfish20g]

Pls help me figure out what's going on. I have a year-old 20G nano reef with 1 clownfish, 1 yellow clown goby, 1 peppermint shrimp, and several blue legged hermit crabs. I would notice my clownfish had an occasional torn/nipped fin overnight or a patch on its side that looks like something picked at it. I ruled out any fin rot or brooklynella because it didn't look like those, and the clown healed after a week or so. Also, this would happen occasionally over 10 months.

Until one day the clownfish disappeared, I couldn't find it, so I presumed it dead and eaten by the clean up crew. I waited a month or so and introduced a new clownfish to my tank. After a few days, I noticed the same patch/damage to the side of its body like I saw in the previous clown. My theory is that the shrimp or crabs are picking at it at night, although my goby never had these issues throughout all this. What should I do?

Also I don't feed my clean up crew directly, only if food hits the sand before the fish eat it (which is not often). All water params normal (no ammonia/nitrates, low nitrates, normal magnesium, kH, ph, etc)

 

[fishguy242]

hi ,pics would help us help you.

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[vetteguy53081]

Pls help me figure out what's going on. I have a year-old 20G nano reef with 1 clownfish, 1 yellow clown goby, 1 peppermint shrimp, and several blue legged hermit crabs. I would notice my clownfish had an occasional torn/nipped fin overnight or a patch on its side that looks like something picked at it. I ruled out any fin rot or brooklynella because it didn't look like those, and the clown healed after a week or so. Also, this would happen occasionally over 10 months.

Until one day the clownfish disappeared, I couldn't find it, so I presumed it dead and eaten by the clean up crew. I waited a month or so and introduced a new clownfish to my tank. After a few days, I noticed the same patch/damage to the side of its body like I saw in the previous clown. My theory is that the shrimp or crabs are picking at it at night, although my goby never had these issues throughout all this. What should I do?

Also I don't feed my clean up crew directly, only if food hits the sand before the fish eat it (which is not often). All water params normal (no ammonia/nitrates, low nitrates, normal magnesium, kH, ph, etc)

Sounds like an aggression issue but a you tube video would help to see the damage you mention. Have you noticed any fighting or chasing?
If another clown, hierarchy where the larger of the two will be a bully.
What other fish are in with it?
One thing you can do to identify aggressor is to set your cell phone on video mode for about 30 mins and drop a little food and walk away - YOU MUST walk away as they know youre there. Often the aggressor is a bully at feeding time.
Review the video and see who it may be

 

[Mr. Mojo Rising]

Its a real stretch for me to think the crabs and shrimp are attacking the fish at night... fish don't really sleep, if something goes near the fish or touches it, the fish will move.

Can we see a tank pic? Pics of the clown will help too to rule out disease.

 

[Jay Hemdal]

Weird - sure sounds like aggression, but the goby and the CUC are not likely suspects.

 

[plantscoralsfish20g]

Here's a photo and a video. The patch on its side has already gotten smaller than it was a couple days ago. My peppermint shrimp has gotten massive, imo it could do some damage.

 

[Jay Hemdal]

Here's a photo and a video. The patch on its side has already gotten smaller than it was a couple days ago. My peppermint shrimp has gotten massive, imo it could do some damage.

The notch in the fin sure looks like aggression, but the oval mark on its side doesn't really look that that to me.

I normally don't worry about cleaner shrimp causing issues, but aquarium animals often do not act like I expect them to (grin).