Oligolepis acutipennis

The Sharptail Goby is a fascinating fish known for its pointed fins and active personality. It's not a freshwater fish, but instead lives in 'brackish' water, which is a mix of fresh and saltwater. This makes it a great choice for someone looking to try something a little different from a standard community tank. Keeping them is considered moderately difficult, mainly because you'll need to manage the salt level in their water. They are bottom-dwellers, spending their time exploring the lower part of the aquarium, so a soft, sandy substrate is best for them. These gobies are social and feel most comfortable in small groups of three or more. While they get along with their own kind, they can be a bit territorial, so it's important to provide plenty of space and hiding spots. They are not picky eaters and will happily accept a variety of foods that sink to the bottom, like special pellets, or frozen treats like brine shrimp and bloodworms. A key thing to remember is that Sharptail Gobies are known jumpers! A secure, tight-fitting lid on your aquarium is absolutely essential to keep them safe and sound in their home.

The Sharptail Goby, Oligolepis acutipennis, is a captivating benthic species originating from the Indo-Pacific, making it a unique addition for the intermediate hobbyist. Its 'medium' difficulty rating stems primarily from its specific environmental needs, rather than a delicate constitution. The foremost requirement is a stable, low-end brackish environment. This involves mixing marine salt with freshwater and using a hydrometer or refractometer to maintain the correct specific gravity. Drastic fluctuations in salt content can be stressful, so consistent water changes are key. The tank setup should replicate their natural estuarine habitats. A low-flow water current is preferred, preventing them from being buffeted about. Given their classification as a bottom-dweller, a fine-grain sand or smooth, small-gauge gravel substrate is crucial to protect their delicate undersides and allow for natural foraging behavior. Their territorial nature, even within a shoal, necessitates a tank with a generous footprint. Ample hardscape, such as driftwood, smooth rocks, and caves, should be provided to break lines of sight and allow each goby to establish its own territory, which mitigates aggression. This species has a notorious reputation as a 'tank escape artist.' This behavior is likely an instinct for navigating tidal pools, meaning any gaps in the aquarium lid, including those for filters and heaters, must be securely covered. As an omnivore, the Sharptail Goby's diet should be varied. While they eagerly accept high-quality sinking pellets, their health and vibrancy are best supported by a regular supply of frozen and live foods. Feeding them daily is sufficient to support their moderate metabolism. When selecting tank mates, it is vital to respect their territoriality and bottom-dwelling habits. Ideal companions are other peaceful, brackish-tolerant species that occupy the middle and upper swimming zones, such as certain species of mollies or glassfish. Avoid keeping them with other competitive bottom-dwellers. Breeding in captivity is considered a significant challenge, likely requiring specific environmental triggers such as seasonal changes in salinity or temperature, making it a project suited for expert-level aquarists.

Oligolepis acutipennis is a fusiform-bodied member of the Gobiidae family, endemic to brackish water ecosystems of the Indo-Pacific. Its physiology is adapted to oligohaline and mesohaline conditions, demonstrating a euryhaline nature, though it thrives in stable, low-salinity environments rather than fluctuating ones. Successful husbandry requires maintaining alkaline and moderately hard water to replicate its native biotope. Its designation as a benthic species dictates specific housing considerations; namely, a low-energy hydraulic environment and a substrate that allows for natural foraging without causing dermal abrasion. The species' social structure is notable, exhibiting a combination of shoaling behavior and intraspecific territoriality. While a minimum social group is necessary for the fish's well-being and to elicit natural behaviors, conspecific aggression requires a habitat with complex structures to provide visual barriers and delineate territories. This behavioral dichotomy suggests a stocking strategy that prioritizes horizontal tank space over volume. A significant behavioral trait is its propensity for escaping the confines of an aquarium, a likely exaptation from navigating intertidal zones. This requires exceptionally secure tank coverings in a captive setting. From a metabolic standpoint, O. acutipennis has a moderate rate of metabolism, oxygen consumption, and subsequent waste production, culminating in a bioload factor of 4.0. This quantitative value is useful for calculating filtration capacity and stocking density in advanced aquaculture systems. The species is an omnivore, requiring a diet that includes both plant-based matter and protein from sources like crustaceans and worms. The 'difficult' breeding classification in captivity implies a complex reproductive strategy, possibly involving specific environmental cues or a pelagic larval stage with distinct dietary and haline requirements, presenting a subject for further reproductive biology research. Its IUCN status of 'Least Concern' (LC) indicates a stable and widespread wild population, suggesting that ethical collection for the aquarium trade does not currently pose a threat.