Figure Eight Puffer

A distinctive feature of this group of fish is their ability to inflate themselves into a ball covered with many spines when they feel threatened. In their normal state, the fish's body is pear-shaped, and the fins are quite short. The coloration consists of a combination of white, brown, and yellow hues. The latter form a pattern on the back resembling the number eight, which gave this species its name.

The natural habitat of this fish is Southeast Asia. In the wild, Dichotomyctere ocellatus is found in the lower reaches of the Mekong River, which flows through Cambodia, as well as in the river systems of peninsular Malaysia and Borneo. In addition, it inhabits brackish coastal waters. It prefers areas abundant in shelters, such as mangrove thickets.

This fish species typically exhibits a peaceful and friendly disposition. It can successfully coexist with many other species of comparable size, provided they are able to live in brackish conditions. Examples of such tank mates include various livebearers, such as platies and mollies. However, it is advisable to avoid keeping this pufferfish with overly active, and especially aggressive or territorial, fish species.

It is important to note that this species is not freshwater. Although the pufferfish can temporarily adapt to fresh water, for its full and long-term maintenance, it is necessary to create a brackish environment with a salt concentration of about 5–8 grams per liter. The minimum aquarium volume for one figure-eight pufferfish starts from 50–60 liters. When setting up the aquarium, multiple shelters should be provided, for example, using driftwood, caves, or grottoes formed from piles of stones. These fish are very sensitive to nitrites and nitrates — products of the nitrogen cycle, which are especially dangerous in brackish water. Thus, the uninterrupted operation of the filtration system and regular scheduled aquarium maintenance become crucial. Care procedures must be performed very carefully so as not to startle the fish. If it gets scared and inflates, taking on a “ball” shape, there is a significant chance that other aquarium inhabitants may accidentally be harmed.

In the natural habitat of this fish, the diet consists mainly of benthic invertebrates: mussels, snails, oysters, as well as small crabs and other crustaceans. To successfully cope with such hard prey, pufferfish have a specific “beak” capable of crushing strong shells. This “beak” continuously grows throughout the fish's life, compensating for natural wear. Therefore, when kept in a home aquarium, it is important to provide appropriate nutrition. Fresh or frozen shrimp, as well as various types of snails, will be an excellent choice.

Breeding in captivity is considered extremely difficult and rare. Information about the process is limited, as successful cases are isolated. It is known that these fish are substrate spawners: eggs are laid on flat surfaces, such as stones or decorative elements. The male cares for the offspring, guarding the clutch and fanning it until the larvae hatch. Spawning stimulation in home aquariums is practically unstudied, and sexual dimorphism is weakly expressed, making pair selection difficult.

The species is highly sensitive to water quality and the accumulation of nitrogenous compounds such as ammonia, nitrites, and nitrates. Poor keeping conditions quickly lead to a weakened immune system and the development of secondary bacterial infections. Pufferfish are susceptible to parasitic infections, including skin and gill flukes, as well as nematodes, which can affect internal organs. Prevention involves maintaining cleanliness, regular water changes, providing a proper diet, and mandatory quarantine for new specimens.

When choosing a fish, pay attention to its activity and plumpness. A healthy specimen should show curiosity, have clear eyes without cloudiness, and a firm body without signs of emaciation or a sunken belly. Avoid fish that constantly lie on the bottom, appear lethargic, or have damaged fins or skin. Since the species is often sourced from the wild, it is important to ensure the absence of external parasites and signs of stress, and to ask the seller if the fish accepts offered foods.