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My 130G tank collection, first some photo's
This is the first one in, originally 10" long, now grown to 14" an Auchenoglanis Occidentalis-Volta river variety: The two Lophiosilurus Alexandri cats, early on.. Right away they started to bury themselves in the gravel, atypical behavior for this species: For the first few months they would exhibit this 'stacking' behavior, taking turns at times, usually in the bright end of the tank, making them easy to feed. Otherwise they would separate and randomly bury themselves anywhere.. At the time I was happy to find another Giraffe cat variant the doesn't get huge like the Congo River varieties, being a male makes it even more inclined to remain smaller.
When I found the L. Alexendri's for sale I jumped at the chance, having kept many Pseudopimelodid's in the past, this species has been 'unobtanium' for decades. Even though very expensive and not much info from past keepers I decided to get a pair and figure out how to keep alive these 2 @ 3 1/2 to 4" juveniles. At first feeding was a challenge, any food items had to fall right in their face to get a reaction, using pellets, shrimp, blood worms, tilapia and live nightcrawlers to begin with. As time went on they seemed to prefer the frozen bloodworms and nightcrawler worms the most so I stuck with that. At one point I could just dangle a live nightcrawler above them and they would swim up too grab it from my hand, especially the smaller one, nice as the last thing I wanted was another type of shy reclusive fish like most of mine are. As of maybe 3 or 4 months ago their behavior and preferred location changed completely, now they both inhabit the dark end of the tank and all that can be seen of them is pair of lips among the gravel or nothing at all when the bury much deeper. I still try to feed them chunks of tilapia that they continued to like and the live nightcrawlers of course, sometimes with no observable reaction. The Giraffe cat has an amazing appetite and will eat what they refuse. In the tank there is a decent population of guppies I maintain in there and presumably that is now the main diet for the 'pac-man cats'. Don't see them much at all any more, only when I have to move them with a net to vacuum the gravel. At a glance they seem to have grown to around 10 or 11 inches by now but are now just a couple more reclusive resident catfishes, at least the Volta is less shy than before so I get to see him on a regular basis...

Great post as always, Kirk! Thank you. How have you determined the gender of the Volta?

Good question Viktor, It was because of you who identified the fish as a 'Volta' variant when posted for sale on MFK that made me decide to buy it as you have reported that they are inclined to remain smaller than other versions of A. Occidentalis. Having searched for scientific ways to determine sexual dimorphism in Auchenoglanidae hasn't revealed much results, even scientific studies such as Revisions of the Genus Auchenoglanis etc. mentioned the morphometrics of each species but nothing on dimorphism. My conclusion of the fish being a male is based upon my experience with 'giraffe catfish' in general and observations with other species of catfish overall. I have had M & F versions of A. Wittei for example the differences became obvious over time. As with many of these fish, male fish are usually appear longer and slimmer compared to females that are more stout, robust and deeper bodied. Usually the profile and dorsal view provides further clues. Since this is my first Volta I have no photos or anything else to compare it to. This fish having a long slender profile leads me to think it's a male, just an 'educated guess' from keeping these fish for many years. In general with catfishes females have smaller heads and thicker girth than males that display larger heads and less girth when compared. The old adage among anglers is "big head-small shoulders are male and small head-big shoulders, female". Being a catfish angler also I can tell the difference among flathead, channel and white catfish at a glance, from experience. That said, it would be easy to mistake an underfed female fish for a male and with little data or photos regarding 'Volta River' fish, it could be that as a 'group' they could be inclined to display a longer slimmer profile than their Congo River cousins. In related species such as in the genus Parauchenoglanis, the dimorphism is more obvious, here's an example: With my Volta fish, it's profile hasn't changed during it's year with me, he/it's certainly well fed on a variety of foods and with such a voracious appetite has grown from 10" to 14" but maintains a 'skinny' and flat bellied overall appearance. Maybe I could attribute my conclusion up to wishful thinking as I hope it's likely a male, inclined to be a smaller fish overall and won't outgrow my tank anytime soon...

Thorough delightful reply as always. Our 6yo Volta male is also 15" give or take. Doesn't grow much anymore. The 8yo female is 20"+. I assume the size disparity is sexual.