Don't house iridescent shark catfish or channel catfish with a Harlequin shark

[Viktor Jarikov]

A video on the topic of parasitic rasp by Synodontis eupterus aka featherfin and by the most common syno hybrid (aka valentiana, zebra, jaguar synodontis, etc.), whose one parent is believed to be the eupterus:

[Fishmandavew]

That is what I would expect a uk “harlequin shark” grow up looking like too. Start off as a lovely variegated pattern but as they get larger this hoes and you end with a black barb with purple spots on most scales. 14” seems to be full grown size from experience. Mine and the 26” black shark were buggers for rasping the irredescent or any grow on koi. Even now my new grow on black shark has started on the scales of smaller grow on koi so it looks something built into their dna. That and chasing fish just for the hell of it. Hence me trying to grow on more bs to occupy the others more )and hope o don’t just get a school of bullies that leave each other alone).

[Fishmandavew]

I find it strange that bs seem to have this rasping built into their dna and yet not all synos do. Seems to be just some and I wonder if for synos it’s a boredom thing, as the cases I hear of it are either in singular fish, in tanks with little or no hiding spots or both. I have 8 eupterus in the pond who have to date never bothered irredescent sharks, koi, giraffe cats or any of the other big cats yet they have “lots” of hideouts in the form of branches rock work and pipes along with each other to keep them occupied.

[Viktor Jarikov]

Thank you, Dave, your input is as interesting as ever.

Our purple labeo is around 9 years old and 20 inches now. If yours topped out at 14" that's quite a bit smaller. Without any grounds I wonder if this might be a sexual dimorphism.

Our two 17" black sharks had been alright with 200 koi in a 25,000 gal for a long time, about a year (had to take them out when the ever-oblivious sturgeon went in). But I never even thought of trying the purple labeo in the 25K for the fear of this maniac. Black shark has nothing on purple labeo / harlequin shark / variegated shark IME.

The syno "boredom" is an explanation that can be met bounced among our peers. However, some peers that commented on our syno rasp video (the last one above) reported that they had the rasping in heavily planted or decorated tanks. But probably not in such high numbers as the 8 of yours and in far, far smaller tanks than your 1500 gal.

[Viktor Jarikov]

The syno eupterus and the hybrids were caught rasping a sun catfish:

[Viktor Jarikov]