Catfish Corner: Varia

Author: Lee Finley

This month is a “housekeeping” month, and so this column will consist of some bits and pieces starting with a couple of corrections. From there I’ll cover a few varied topics.

Updates and Corrections

In the October 2006 issue I had a feature article titled “Spawning Catfishes in Aquaria: Where Are We and Where Are We Going?” A couple of follow-up comments on this article are necessary.

Under the family Erethistidae, I noted that a spawning of one species jerdoni had been reported. A new paper has recently been published covering the erethistids in part, and the name used must be changed. The genus name Hara was placed in synonymy with Erethistes, so the new name of the species is Erethistes jerdoni. (Reference: “Genera of the Asian Catfish Families Sisoridae and Erethistidae. Teleostei: Siluriformes.” Alfred W. Thompson and Lawrence M. Page. Zootaxa 1345: 1-96. Published 10/30/06.)

And under the family Plotosidae I noted: “To the best of my knowledge none of the freshwater plotosids of Australia or New Guinea have been spawned in aquaria.” I received an email from TFH writer Gary Lange telling me this was not the case, but no details were provided. Luckily I ran into old friend and Australian native Peter Unmack at the recent catfish convention and queried him about this. He told me that Neosilurus gloveri, the Dalhousie catfish, has in fact been spawned in the aquarium, although it is not an overly common event. Thanks to Gary and Peter for their input on this topic. Peter is going to be sending me an article regarding the spawning of this small species, and I will cover this in a future column.

The Eyes Don’t Have It

Taxonomic work with fishes using studies including various molecular, protein, and chromosome analysis are increasingly evident (see my column on Lake Tanganyikan SynodontisTFH November 2006). Such studies often provide valuable information useful in regard to taxonomy and other areas such as conservation biology. But they can also offer up conundrums. Such is the case with a recently described species of madtom catfish. Work as of late has been looking into cryptic (hidden) species of these small North American ictalurid catfishes. In the sense used herein, “cryptic” means hidden among the population of a previously described species. Often the differences between such species are small and may have previously been considered to just be an acceptable variation within the species.

The new species that has been described, Noturus maydeni, was separated out from a previously known species, N. albater, commonly known as the Ozark madtom. The two species are geographically isolated, which certainly helps. But according to the authors, they cannot be physically separated by standard taxonomic morphological techniques. In other words, they are physically the same—but they are different species. The stated differences for N. maydeni are based on chromosome, protein, and DNA characteristics. It is this kind of brave new world that aquarists may have to increasingly deal with in the future.

There are already hints of such things within the commonly kept Corydoras catfishes. Some work of a few years ago identified different chromosome numbers and morphology among three geographically isolated populations of C. nattereri. It was noted there also that the populations could not be morphologically distinguished.

As time goes along I am sure that we will see more of such work. How it will be handled on the basis of aquarium fishes remains to be seen. But certainly, if we as aquarists can obtain groups of various catfishes from known localities it will be to our benefit to keep them as separate and distinct groups. Killifish keepers, and many cichlidophiles, have been doing this for years and it is probably time for serious catfish keepers to fall in step. (Reference: “The challenge of truly cryptic diversity: diagnosis and description of a new madtom catfish,” Ictaluridae: Noturus, Jacob J. Egge and Andrew M. Simons. Zoological Scripta, 35(6), November 2006: 581-595.)

One Neat Loricariid

Elsewhere in this issue I have given a brief overview of the recent All-American Catfish Convention that was presented by the Potomac Valley Aquarium Society (“Aquarium Hobby News,” p. 143). The space was limited for that piece, so I would like to share with you herein a picture and note or two on my favorite catfish of the convention. This is Pseudohemiodon apithanos, the so-called chameleon whiptail catfish.

There were two of the chameleons at the convention, but they were not in the show; they were in the “for sale” setup presented by George Fear of Shark Aquarium (Hillside, NJ). They were a hit at the convention, and I think that one of them was the first fish sold.

If ever there was a loricariid to be viewed from the top, this is it (see photo). The picture pretty much speaks for itself, excepting for two considerations: 1) the grayish areas of the body are, when the fish is feeling spunky, often infused with a bluish to greenish sheen; and 2) when the fish is earning its common name. The ability of this species to change color is quite amazing and it can be seen, depending on its mood, ranging from half to fully dark in color. It can be quite a show!

Pseudohemiodon apithanos  Basics

Pseudohemiodon apithanos is a western Amazonian species and is known from Ecuador and Peru, with the commercially available specimens originating from Iquitos, Peru. This is a large species with some individuals reaching almost a foot in length (SL), although most imported fish are less than half that (or a bit smaller). It is primarily a sand-living species and this should be kept in mind when maintaining the fish. They very much like to bury themselves, so ideally you should provide them with a sand substrate of at least 1½ to 2 inches deep.

Like many sand-dwelling loricariids they tend to be more carnivorous in nature. The stomach contents of wild specimens have been noted to contain the debris of insects, caddis-fly larvae, and snails. Keep this in mind and feed them a higher protein diet than you would for most loricariids. In the aquarium they are quite adaptable and will eagerly take a wide variety of prepared and frozen and/or freeze-dried foods. They typically come from areas that do have a good current, so also consider this in regard to the aquarium setup.

Like other Pseudohemiodon species, P. apithanos is a male lip brooder, so some fascinating experiences await the aquarist working towards breeding this fish.

Granted this is not an inexpensive fish, but it is definitely special and worth considering.

Internal Fertilizing Catfishes

In general terms the South American auchenipterids (driftwood) catfishes are the group generally thought of as the internal fertilizing catfishes. But they are not alone in this interesting mode of reproduction. It has been realized for some time that the miniature catfishes of the South American family Scoloplacidae (one genus, four species) also share this reproductive style. Very recently some new work has been produced in this area, and it further confirms the reproductive mode in these fishes. Although there are some anatomical and morphological similarities in the reproductive “machinery,” there appears to be no relationship between the scoloplacids and the auchenipterids.

Although the species of the genus Scoloplax are locally very common in many areas, their extremely small size (all species are smaller than 2 cm SL) does not make them a good candidate for commercial collecting. Add to that their typical habitat (leaf litter) and you can pretty well forget any commercial shipment. The only outside chance for finding them amongst imports might be in shipments of smaller banjo cats Bunocephalus spp.

But it is still nonetheless interesting to know their breeding mode and we can hope for someday seeing at least modest supplies of these fascinating little catfishes. (Reference: “Spermidgenesis and introsperm ultrastructure of Scoloplax distolothrix, Ostariophysi: Siluriformes: Scoloplacidae.” M. A. Spadella, C. Oliveira and I. Quagio-Grassiotlo. Acta Zoologica 87(4). October, 2006: 341–348.)

My Confession

In last month’s column I mentioned winning a bucket containing four large Mystus leucophasis (Asian upside-down catfish) at an auction. I did not mention that there was no tank available for them. This is not exactly a good situation, and I know better. But such things do occasionally happen and we need a course of action to handle this and make sure that the fish get good treatment. So I’d like to offer a few thoughts on the situation.

I have previously discussed the necessity of a quarantine tank. In the case under discussion I ended up using a quarantine bucket. It’s like a tank, just a bit smaller. The four fish did not look particularly stressed, so upon arriving home I did a 50-percent water change and used a fine net to remove some feces. I then added some ammonia remover to take care of any buildup of this dangerous byproduct. Next I added a few pieces of suitably sized PVC pipe as hiding places, put two working airstones in the water, and tightly covered the bucket (to prevent any jumping). Good night—see you in the morning.

Early the next morning (and much fresher than I had been the night before) I set up from scratch a 50-gallon tank for the four Mystus. Getting everything ready took a couple of hours and the fish were released into their new home, none the worse for their day and night in the bucket. In that it was a brand new setup, I took two large box filters and filled them about ¾ full of live gravel to provide biological filtration. I let the fish adjust for the day before providing their first meal. They were, and are, doing fine.

Should you bring home fish when you don’t have a tank ready for them? No. But, if you have no choice can you do it? Yes. Just think it out logically and remember that a bucket is just an aquarium that you can’t see through.