Any idea?

[Baginert96]

I have just introduced 3 new smaller clown loaches to my 15 year old clown loach. They won't leave him alone, it's almost like they are nibbling him and riding his back. Is this normal? Need help, never used a forum before but don't know what to do.

[NancyD]

I have not had that experience but I have read of others with similar loach behavior. Always with small loaches introduced to larger. It seems the small just can't get enough contact with the larger loach. Not just with clowns as I recall. I forget what it was called, ghosting or shadowing or less likely just following I think.

As I recall the shadowing small loaches didn't hurt or harass the big loach too much. The big didn't seem to mind the attentions. It's been a long time, I wish I could remember just when.

I don't think you need to "do" anything. Maybe a few more hiding places in case the big loach would like to get away for a break from all the youngster's extra attention. I don't remember if the little 1s quit that behavior after a while. Sorry, I wish I could be of better help.

[redshark1]

What are the sizes (total lengths) of the fish?

Clown Loaches reach sexual maturity at 4 inches total length.

Could it be reproductive behaviour?

From what you describe I think it may be wise to separate the fish.