Plotosus canius? What's the fibrous structure behind anal?

[Viktor Jarikov]

I bought two of these from Raymond Chan of AmazingFish in the Summer of 2016 at ~3"-4". They reached about 14" today. I am interested in ID confirmation and also I'd like to know what's that red fibrous structure behind their anus? At first I got super-alarmed and thought they had intestinal worms, like callamanus worms but then I saw they defecate from a pore anterior to that, that is, the anus is closer to the pelvic fin base than that structure. You can see that in the pics below. They both have this structure of about the same size and looks.

They eat exceptionally well and overall look very healthy.

Also, how bad is their venom? Would a puncture wound really always result in a swelling and gangrene?

[Viktor Jarikov]

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[Silurus]

That's the dendritic organ, a structure found in marine plotosids (and very few freshwater species). It apparently functions in osmoregulation.

[Viktor Jarikov]

Thank you, HH. I will assume that you agree with the ID.

Can anyone answer my venom question?

[Viktor Jarikov]

bump

[Jools]

I guess you need Auddy B, Gomes A: Indian catfish (Plotosus canius, Hamilton) venom.
Occurrence of lethal protein toxin (toxin-PC). Adv Exp Med Biol 1996, 391:225-
229. - however the studies of these kinds focus on how toxic the venom is to other organisms. I would surmise that a skin puncture would result on a swelling and significant pain. However I don't know about gangrene.

Jools

[Viktor Jarikov]

Thank you so much, Jools.

Sister thread on MFK: https://www.monsterfishkeepers.com/foru ... st-7705207

[Viktor Jarikov]

June 14, 2017 update. Gluttons they are. Probably the top ones I've ever owned. Currently around 18".

Them and their tank mates in a 240 gal:

[Viktor Jarikov]

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[Viktor Jarikov]

[Silurus]

Here is a recent paper on the salt-secreting functions of the dendritic organ.

[Viktor Jarikov]

Thank you much, HH. I am grateful you remembered.