A large, aggressive species, such as a queen triggerfish, is sometimes best kept singlyA diverse community of marine fishes presents quite a visual feast, especially when housed in a reef system brimming with colorful corals. However, in some stocking situations, it’s preferable to avoid the “typical” marine community (if there is such a thing) in favor of a single-species or even a single-specimen tank. Ah, but if you limit your livestock to a single species or specimen, won’t that make for a real yawner of a tank? On the contrary, sometimes systems that put the focus exclusively or primarily on a particular species or individual are among the most fascinating to observe.Here are five circumstances that warrant going single-species or single-specimen: 1. The shy, specialized feeder Seahorses, which are slow, awkward swimmers, shy by nature, and very specialized, methodical feeders, come to mind here. In your average community aquarium, these fish would basically be doomed, as they’d be unable to compete with bolder, faster-moving tankmates for food and would be unable to tolerate the brisk water movement typical of such systems. Not to mention, a community tank of any appreciable size would make it extremely difficult to provide the steady supply and high concentration of suitable food items necessary to sustain seahorses. On the other hand, in a small dedicated system with very gentle current, no competition for food, and suitable “hitching posts” to cling to, a group of seahorses can make for a truly mesmerizing display
Rock Beauty Angelfish (Holacanthus tricolor)On one of my earliest dives down in the Florida Keys back in the 1990s, a gorgeous yellow and black angelfish caught my attention as I drifted over a section of reef. In my mind’s eye, I envision the angel hovering boldly above a large barrel sponge, but I can’t be sure whether that’s actually how it happened or just an idyllic memory. In any case, I was taken with its distinctive appearance and wondered whether it might make a good aquarium candidate. As anyone familiar with the fauna of the tropical western Atlantic has already guessed, the angel I saw back then was a rock beauty (Holacanthus tricolor)—a species that, unfortunately, tends to fare poorly in marine aquaria and is generally best left to advanced fishkeepers or, better yet, in the ocean where it can beguile other divers. I’ll get into why in just a moment.Physical traits H. tricolor is laterally compressed (flattened from side to side) and, in typical angel fashion, sports a sharp, backward curving spine on the gill cover (operculum). As alluded above, this species is yellow on the anterior portion of the body and on the caudal fin and black from behind the gills to the caudal peduncle (base of the tail). The margin of the anal fin, the edge of the operculum, and the opercular spine are orange.
Overfeeding is sometimes necessary to entice a finicky fish to eat, especially if they have little nutritional reserve to begin with, such as butterflyfishYou’ve heard time and again, here at Saltwater Smarts and elsewhere, that overfeeding is one of the surest ways to cause ill health in fish and pollute your aquarium water. The usual recommendation is to offer foods in very small quantities that the fish can consume within just a few minutes. And when it comes to reef systems, we tend to be especially sparing with fish food in order to maintain the lowest possible level of dissolved nutrients. While it’s generally good advice to feed fish sparingly and judiciously, there are certain times when it doesn’t pay to be stingy with the victuals. In fact, sometimes you really have to feed on the heavy side and then step up your water changes and other water-quality-management techniques to compensate for the increased dissolved pollutants. Here are just a few examples off the top of my head:When feeding a finicky fish in quarantine Of course we’re supposed to make sure fish are eating at the LFS before we acquire them, but over the years I’ve had various specimens simply turn off the “feeding switch” upon arriving in quarantine (and in a few cases after being moved from quarantine into my display tank), possibly due to the stress of transfer or because they simply didn’t recognize the stuff I was offering as edible. When this situation arises, it can take a lot of coaxing with different types of food at various times throughout the day to entice the specimen. In other words, you may end up introducing a lot more food to the system than is typically considered acceptable before the fish finally resumes feeding.