A Brackish Background
Before we delve into Mono Sebae, it’s worthwhile to take stock of the brackish aquarium hobby as a whole. It is an extremely underappreciated and overlooked niche within our passion, but it’s understandable how we got here.
The brackish water offerings at most aquarium shops, if they even bother to carry brackish fish at all, are often relegated to a single tank. It is easy to guess why; the choices are a bit limited. Thinking of brackish water fishes conjures only a handful of occasionally-available fish species including some of the various Puffers, Gobies, Scats and Monos. Maybe if you’re lucky Archers, Mudskippers, Four-Eyes (Anableps), Toadfish, “Freshwater” Frogfish, along with Green and Orange Chromides, get casually thrown into the “brackish” group and at times show up at your LFS.
Of course, there are some brackish species erroneously passed off by the aquarium trade as freshwater species, thus destined for improper husbandry at the hands of uninformed aquarists. As a prime example, the “Columbian Sharks”, a.k.a. “Silvertip Sharks” or “Blackfin Sharks” are neither freshwater fishes nor sharks; best known as Ariopsis seemanni, they’re a marine catfish species too often suggested as being freshwater, yet most decidedly are brackish fish that as adults are suggested to be best in full strength saltwater. Additionally, despite being well-suited to brackish environs, we don’t tend to think of the Mollies as “real” brackish fishes (and while they can be kept in purely freshwater, overwhelmingly they seem to do better with a little aquarium salt added, and most all can be brought to full strength saltwater). There are of course native brackish species such as the Sheepshead Minnow (Cyprinodon variegatus) and the lustworthy Diamond Killifish (Adinia xenica) to add to the diversity of brackish options, but when have you seen either of these at the LFS, or even through online specialty sources?
It doesn’t help that “brackish fish” often get lumped together by their singular (and perhaps over-generalized) shared preference for salinity levels far less than full-strength saltwater. The implication being that “oh, they’re brackish fish, just throw them all together.” Any hobbyist that does simply throw whatever brackish fish are available together (because they’re the only ones available) is probably going to deal with compatibility issues and quickly become discouraged. Obviously, not all brackish species are compatible, so even when we exhaust all possibilities to find candidate species, aquarists are still quite limited within the subset of species as they start choosing.
The requirement to add salt to the water for brackish fish certainly could be a stumbling block for less experienced & beginning aquarists (you may or may not remember the days when things like the nitrogen cycle seemed like daunting post-doctoral biochemistry, so cut the newbies some slack!). The limited options for livestock certainly add another reason for novice aquarists to skip the brackish water aquarium department. In fact, it very well could be that people get drawn into brackish water aquarium keeping primarily by the charismatic Pufferfishes and Archers more than any others. These oddball fishes have enough visual appeal and interesting behaviors going for them that people will seek them out.
As a result, brackish aquariums aren’t commonly the target of our collective aquarium keeping efforts. It’s therefore not surprising that brackish fishes aren’t generally the target of breeding efforts either.
When we also consider that many brackish fish have life cycles that emulate many marine fish species, and may require a range of salinity from spawning to hatch to grow out and maturity, it’s not surprising that the complexity would prevent a more straightforward approach that most freshwater fishes require. Thus, a freshwater aquarist trying to apply freshwater-honed techniques and ideas to many of the available brackish species is set up for failure from the get go. Indeed, when it comes to breeding many of the aforementioned species, it is the experienced marine aquaculturist who has more of the appropriate experience and resources at his or her disposal.
Enter Monodactylus sebae
Monodactylus sebae, often simply shorthanded Mono Sebae as a common name (and also known as the African Moony), is the less-commonly available of the two popular Mono species (if we can actually call any brackish-water fish “popular”). The related Monodactylus argenteus, the Silver Mono, is much more commonly seen, which makes sense given its wide Indo-Pacific range, whereas M. sebae is native to Africa’s west coast (the Atlantic side). Both are members of the family Monodactylidae, the Moonyfishes or Fingerfishes. The two other Monodactylus species seem completely absent in the aquarium trade, as are the two related Pomfreds / Pomfrets of the genus Schuettea. (That said, the Eastern or Ladder-finned Pomfred is quite the looker!)
Most aquarium references suggest that Monodactylus sebae is less hardy / more disease prone than M. argenteus, although the reasons for this reputation could stem from past histories of improper care, or the presumably less developed supply chain of aquarium fishes coming from West Africa. Combined with spotty availability and presumably stricter demands on care, it is not surprising that M. sebae is generally the more expensive of the two Mono species in the trade.
M. sebae reaches about 8″ in length at the most, but most people talk about this species in terms of height, rather than length. It is not unheard of to read about M. sebae reaching a foot (12″) or more in height. With these figures in mind, most recommendations for Mono aquariums are big; 125 gallons to 250 gallons or more. These recommendations stem not only from the size of the adults, but their very active nature.