In bed, lights off, wide awake? Instead of pill or a drink, how about a tank?
There are a lot of great fish that we seldom see, because they live in a different world from ours. Not that they live in the water, but that they live in the dark. Some of us already know that our usual daytime friends may look a lot different if we turn the lights on in the middle of the night- their colors and patterns can fade and become blotchy. They can't close their eyes because they have no eyelids, but do go into a state very like sleep is for us, little or no activity, slower breathing, sometimes color changes (which we can't do). Some fish however, wake up when the lights go out, because in the wild this is their activity time. Some of these nocturnal (night active) fish are really crepuscular (twilight active). The fish we have swimming around in most of our tanks are diurnal (day active). If we have our tanks on a regular light cycle either because we are very regular in our habits, or because we have our lights on timers (that one is me), most of the nocturnal and crepuscular fish will become active a bit before the light go off. We can enhance the effect of their "knowing" what time it is by feeding them in the period prior to their "night". Then the tanks' lights go off and we go to bed, some of us even go to sleep.
But for those who do not go to sleep easily, or who wake up in the middle of the night and can't get back to sleep, wouldn't a tank be better than counting sheep? We can cheat here. We can't see in the dark, most fish can't either, but some can do a lot better than we can. Ever noticed how many catfish have big eyes? Guess why? Yup, like opening the lens of your camera, they gather more light and can see when we can't. We turn on the tank light and they go back in hiding. This is where the cheatings come in. We can see in red light. Red is the longest wavelengths of visible light for people, but by being the longest wave lengths, it is diffracted the most and penetrates the least in water. Blue, the shorter wavelengths, penetrates best into water. Blue light is likely to appear bright to the fish. Most fish can't see red light. So, we rig a small red light that is on after the regular tank light is off. We can see them and they can't see us. Bingo! A whole new world is open that we haven't seen before. The catfish that never moves when it is light can be out gliding around the tank as smoothly and silently as a ripple on a pond.
One group of cats especially well suited to the insomniac's tank are the woodcats, or driftwood catfish. They are from the family Auchenipteridae, an unfamiliar group of scaleless cats with boney helmets, who add to their strangeness by practicing internal fertilization and delayed egg-laying. Most of the group, but not all, have long-based anal fins. Most of the group, but again not all, have adipose fins. Most of the group are outstandingly plain to drab. They tend to look like wood twigs (Hey, a name maybe?). They are nocturnal, nocturnal, nocturnal. And I'm trying to persuade you to set a species tank for a fish that hides in a woodpile all day, who looks like a stick, and will be happy to have any fish for dinner who is up to a third his size? Yup, you got it. The kicker is that once these fish think it is dark, they are out patrolling the tank ceaselessly but not frantically. They are among the most graceful swimmers available. My guess on this smooth, stately gliding around the tank is that this produces less disturbance in the water, so is less likely to alert potential prey items that there is a mouth on the move in the neighborhood.
These are not common fish in the trade. Your local fish store staff is likely to react with a blank look and a flat "Huh?". They are seasonal imports from South America and are seldom really identified (as is the case with plecos, the importer/wholesaler/retailer is likely to attach just about any label that strikes their fancy). Some are pretty small, say about 3" adults, most are 4-6" adults, a few not rare ones are 8". At least one uncommon species is 12" or more.
In the hope that you will be able to get some of the few that are usually identified, one small one is Tatia aulopygia, the Black Pygmy Driftwood. These are usually plain black, not very bark-like, sometimes with scattered white scales. They won't grow past 3". I have not kept this fish, but from my reading it sounds highly desirable, and may be among the mostly likely to reveal the requirements for tank breeding. The commonest fish seen at your LFS from the group is likely to be Auchenipterichthys thoracatus. This is marketed as the Midnight Cat, or in my area, as Zamora Cats. Dark bluish-gray bodies, blackish markings on fins, and more or less white spots scattered or in rows on their bodies. The ones with the most and most regular white spots are likely males. Secondary sexual characteristics for the group as a whole are seasonal (as with Loricariids)- males develop elongated and modified anal fin spines (for fertilization a la livebearer mode), elongated dorsal fin spines, and sometimes barbel modification. These are not likely to be seen in dealers' tanks, but possible. The Zamoras are from Peru, can grow to about 5" and three of these in a 20L or five in a 30L/40L are spectacular under red light light. This was my test group for the red-light district and more than completely satisfactory, once you adapt to the tank appearing empty during the day. I don't spend much daylight in the bedroom anyway. Parachenipterus galeatus, with the informative common name of Driftwood Catfish, is larger, up to 8" reported, though mine did not grow quite that big in the under two years I kept it. It is blotched and mottled with dark-brown-to-black-on-lighter brown, and very convincingly bark-like. I suspect mine was male due to the clarity of his markings, but he never developed secondary sexual characteristics (immature?). I felt he needed more room than the 30L I had him in, so traded him off to another fishkeeper promising him a 50 (with a Chaca, lots of live food). He was purchased under the identity of Trachelyichthys decaradiatus, which should have been a 3" spotted pygmy driftwood. Wrong.
There are two or three oddballs in the group. The Jaguar Cats, standard or black, are included with the driftwoods, but do not quite fit. The Jaguars are usually correctly identified, tend to be quite pricey when they are available, and are arguably among the best-marked catfish around in any family. The adipose fin is much different from its' supposed relatives, very long-based, and the fish is overall much chunkier than the others. I have not kept it, but observed it in a friend's tank, and it does not have quite the grace of the more slender driftwoods, though it tops them in looks. The ultimate driftwood cat has to be the Eel Driftwood, at least a foot long, lacking an adipose fin. Another "someday" fish, as they really need space. I just don't think I can convince my spouse that we need a 72x24x24" tank in the bedroom which would look like an empty underwater woodpile in the light.
So, nuts and bolts: What tank? The best bet is something long in relation to its height-we are after relaxing grace and beauty here. 20L (30"), 30L (36"), 33XL (48"), 40L (48") all make great night lights. Bigger is always good, but beyond these listed I think it is hard to keep the support equipment quiet.
Substrate? Gravel or coarse sand- not blasting sand- many of these fish are a little sensitive to rough substrates. Maybe even fine sand, if you are really conscientious about vacuuming and have no filter intakes near the bottom of the tank. Probably the best overall choices are coated aquarium gravels- no skin problems for me using these.
Filtration? This will depend in part on the tank size and the fish selected, but we are going for silent running here, so the basics are internal or sealed external filters. For internal filters I like Eheim or Fluval internal canisters. I also favor redundancy, so I choose to use two, even if one would do. In the 20L I use two Fluval 2s, one at each back corner: one mounted at the side wall aimed directly along the back of the tank; the other in the opposite back corner, mounted on the back wall, aimed at the front center of the tank. This sets a somewhat circular current in the tank. Both of these should be mounted below the surface of the water sufficient to produce rippling on the surface without splashing. For external canisters I like Eheim again, but if you have a favorite flavor that is different, use it, so long as it is quiet. Set the water return below the surface again to ripple without splashing.
Furnishing: Will vary with the particular fish again, and whether single specimen or school, but in general will be bogwood or rocks, low light plants (Java Fern and Java Moss) and lots of swimming room. For a single specimen, a sizable tangle of bogwood at one end, occupying say 1/3 to 1/2 the tank length and restricted as much as possible to the back 1/2 of the tank. Attach Java Fern with rubber bands or cotton thread to the wood. Before the rubber bands or thread rot, the plants should be attached to the wood. Visually divide the rest of the open tank space in half. At that point place a driftwood "fence post" (as one of the LFS staff so aptly, if in-elegantly, calls them). These are the common short upright slate-mounted driftwood pieces that are nearly the cheapest wood available for tanks. To this fence post attach a couple of clumps of Java Moss, again by rubber bands or thread. A few pieces of Java Fern can be filled in the open spaces near the back of the tank. These can be either planted in the gravel IF you keep the rhizome horizontal and fully exposed above the gravel, or attached to a low rock resting on the gravel (I like the latter technic, but the roots will extend into the gravel with time). If you are to have a school, scatter more bog wood the length of the tank, with a fence post or two to break up the line of horizontal wood. Avoid symmetry. I promise you will not like it. If the bogwood is piled over half the height of the tank at one end, make sure the other end is well less than half the height. Attach plants here and there, more of one type than the other, and not alternating, please. I like mostly Java Fern, Java Moss as accent. Plain backgrounds will look better than a photographic one on this tank.
Lighting: This is the fun part. A single strip with the longest possible bulb (full spectrum, please) is used along the BACK of the tank. That's where the plants are, right? The single tube is low to very low light, we are using low light plants and cheating a bit by having them "planted" on wood well above the substrate (nearer the meager light). Plug this into a timer set for 12 hours/day. The On/Off times should fit your schedule. Now, we need a night light. If you have a "dead" strip light, throw away the old electrical components and replace them with one or two low wattage night lights. I have a couple if night lights that came with two Christmas-candle sized bulb that seem to offer much longer bulb life than the single-bulb types. Replace the clear bulbs with red Christmas lights. If you are unhandy and the foregoing is too much for you, get the smallest available fluorescent strip and cover the face with the darkest available red filter. Stained glass supply shops can provide the glass and a framing shop or glass store can cut it to fit for you. Several layers of red cellophane could also work, or a dark red gel from a theatrical lighting supplier. I use plastic tape to secure the filter to the fixture. When it starts loosening, replace the tape. Put this unit on the front of the tank, over the swimming space. Plug it into another timer, set to turn on the same time the "day" light turns off. Off time for the night light is your choice, but should be by the time natural light comes into the room. The nocturnal fish will take cover from non-red light regardless of whether on not the tank is red-lighted.
Maintenance? These fish are straightforward in requirements. In common with many cats, they are quite adaptable in water chemistry. I have heard of adaptation problems with young cats, especially young Jaguars, so if your water is different from that in your dealer's tanks, use a slow drip for the initial introduction. You may want to avoid large-scale changes on young fish. My routine change is only 10-15% per week, so I have seen no problems. Sponge filters are rinsed periodically, fairly often for me as I use these as primary mechanical filters in the internal canisters. External canisters are probably cleaned at approximately three month or longer intervals. I would never crowd a woodcat tank- the aim is grace and peace, an empty country lane, not the expressway at rush hour.
Feeding? This too is easy. In the wild they eat insects, crustaceans, and fry. So feed them that. Sinking carnivore pellets, some FD, frozen bloodworms or scuds, small red eathworms, occasional live brine are all suitable foods. Occasional live guppies, especially fry are good also, but I distrust LFS feeders, so I rear my own.
So, have I convinced you? Are you rushing right out to buy a large night lightlive guppies, especially fry are good "I never see my whatever catfish" you may want to consider that you are just looking at the wrong time and under the wrong light. You could be missing a lot.