Practical Fishkeeping July 2022

I AM an unashamed biotope fan, so when I got the chance to feature David Nørholm's delicious Mexican set up (it's on page 16) there was no way I was letting it get away. There's just something about the ‘natural’ look that seems to fit so well with fishkeeping. Perhaps that's also why I'm excited to see former PFK editor Jeremy Gay writing all about nature ponds this month — there's a man who knows the hobby inside out and upside down. And how about an excursion into nature as well? We've got that in the bag with Daniel Konn-Vetterlein documenting his trip to South America in a (successful) search for altum angelfish, with plenty of other aquarium favourites making guest appearances. We're also looking at a classic this month.…

BIOLOGY Convergent evolution OVER THE eight pages that follow, Steve Grant and I each explore some catfish that have evolved entirely separately, continents apart. Despite being so distantly related, some of them look so similar that if placed in front of an unfamiliar eye, it can be difficult for the casual aquarist to tell them apart. Heck, I've even seen catfish veterans get them wrong. This is the work of convergent evolution, and it's worth some prefacing if you're not familiar with it. Convergent evolution might be best explained as the evolution of the same features in species that share no common ancestor. Think of it as an adaptation that's so beneficial, or so intuitive, that organisms independently evolved it for themselves. In the fish world, an example of convergent…

CATFISH Physopyxis ABOUT TEN years ago, my partner yelled at me to come look at something on the television. What I saw there was myself — a tall, thin man with my face, bleached hair to the shoulders, thick-rimmed glasses, Nike trainers, the same wonky teeth, wearing an obscure 80s camouflage jacket only available from Russia. I was gobsmacked; it was me, but it wasn't me. Somehow this man in the south of England had the exact same ‘adaptations’ to the world as I did. I'd imagine that dwarf talking catfish, Physopyxis lyra, would feel something similar if I stuck them down next to Hara jerdoni or Erethistes pusillus (read Steve Grant's take on these amazing fish in the following feature). These catfish live continents apart, but because of their…

ARGUABLY THE most popular catfishes are corydoradins — Corydoras, Aspidoras, Scleromystax. They're small, long-lived, sociable, easy to breed and a whole lot more. But as fantastic as Corydoras are, there are some other catfishes that have some of those qualities, and the mothcats are in that category — dwarves with a distinctly moth-like appearance. So, what are the mothcats? Well, that's not so straightforward to explain. Depending on which ichthyologist's work you follow they are a member of the Asian catfish family Sisoridae, or in their own family, called Erethistidae. I favour the latter. Erethistids are mostly easily distinguished from sisorids by having a long bony process along the lower side of the body, that extends well beyond the base of the pectoral fin. The name mothcats comes from an…

PFK: Hi David, huge thanks for taking time out to tell us about your magnificent tank. What sort of set-up are we looking at here? DN: It's an honour to share my aquarium in this great magazine! Well, first and foremost this is a biotope aquarium, and a biotope aquarium is a relatively close replica of an aquatic habitat — it's a way of imitating nature and trying to get as close to it as possible. This obviously affects the selection of fish, plants, substrate, hardscape, and so on. It is a little slice of nature, if you will, where the fish and the habitat is in focus. How long has it been up and running for? This setup has been running for almost a year now, with some changes…

OCCASIONALLY, IN the recesses of oddball fish stores, you might come across a square-looking, silvery-green or red-hued fish that doesn't look quite like the rest. There's a good chance this will be Scatophagus argus, or the spotted scat. From the off, it should be noted that there are two ‘types’ of spotted scat. Scatophagus argus has a subspecies — Scatophagus argus arromaculatus, offered under the common name of red or ruby scat. Care for both S. argus and its subspecies is identical and outward appearance is the only discerning feature between the two. S. argus has endured, on and off, as a popular aquarium inhabitant for many decades in the aquarium hobby. This can largely be attributed to its relatively easy care (if some basic requirements are met) and interesting…