Dichotomyctere ocellatus (Figure 8 Pufferfish)

Overview

The Figure 8 Pufferfish (Dichotomyctere ocellatus), formerly classified as Tetraodon biocellatus and often called the Eyespot Pufferfish, is a remarkably intelligent and interactive fish. Known for their puppy-like behavior, they quickly learn to recognize their owners and will often beg for food at the front of the glass. While they are incredibly rewarding to keep, they require specific dietary and environmental conditions to thrive.

Distribution and Habitat

Native to Southeast Asia, the Figure 8 Pufferfish is typically found in the lower reaches of freshwater streams and rivers, as well as coastal estuaries across Thailand, Cambodia, Malaysia, and Indonesia. While they are often sold as freshwater fish, they naturally occur in environments that experience slight salinity fluctuations, making a low-end brackish water aquarium the ideal setting for their long-term health and vitality.

Description of Figure 8 Pufferfish

Body shape:

They possess a classic club-shaped puffer profile. Their bodies are stout, scaleless, and highly flexible, allowing them to maneuver efficiently in complex environments.

Color:

The upper half of their body is typically a dark brown to black, overlaid with striking yellow or gold lines and spots. These patterns frequently form a 'figure 8' shape on their back. The belly is a stark, clean white.

Barbels:

This species does not possess any barbels.

Snout:

They have a blunt, rounded snout featuring a strong, beak-like mouth formed by four fused teeth, which is characteristic of the Tetraodontidae family.

Eyes:

Their eyes are large, expressive, and capable of moving independently, giving them excellent vision to spot prey and observe their surroundings.

Fins:

Their fins are relatively small and translucent. They lack pelvic fins entirely, relying heavily on their pectoral fins for precise, hovering movements.

The Tail:

The caudal fin (tail) is fan-shaped and is primarily used for sudden, rapid bursts of speed when chasing prey or escaping perceived threats.

Temper

The Figure 8 Pufferfish is generally considered semi-aggressive. While they are not outright killers like some larger puffer species, they are notorious fin-nippers and can be highly territorial, especially in cramped quarters.

Sociality

Due to their nippy nature, they are best kept in a species-only aquarium or individually. If kept in a brackish setup, they may sometimes coexist with fast-moving, short-finned fish like Bumblebee Gobies, but there is always a risk that the puffer will attack its tankmates.

Activity

These puffers are highly active and curious. They spend the majority of their day exploring the aquarium, investigating decorations, and hunting for small snails or other food items. They require a stimulating environment to prevent boredom.

Keeping and Caring for Figure 8 Pufferfish

Tank size:

A single Figure 8 Pufferfish requires a minimum tank size of 15 gallons. If you plan to keep a pair or a small group, a 30-gallon tank or larger is strongly recommended to minimize territorial disputes.

Water Parameters:

Temperature

Maintain a stable water temperature between 22-28°C (72-82°F).

pH

They prefer slightly alkaline water, with an ideal pH range of 7.0 to 8.3.

Hardness

Water hardness should be kept between 10 and 20 dGH. If keeping them in brackish conditions, a specific gravity of 1.005 to 1.008 is recommended.

Ammonia, Nitrite, Nitrate

Pufferfish are extremely sensitive to poor water quality because they lack scales. Ammonia and Nitrite must always be at 0 ppm, and Nitrates should be kept strictly below 20 ppm through regular water changes.

Lighting

Moderate lighting is sufficient. They do not require intense illumination, but a well-lit tank helps showcase their beautiful patterns.

Water flow

Provide a moderate water flow. While they aren't the strongest swimmers, they appreciate a gentle current that mimics their natural riverine and estuarine habitats.

Decorations and Plants

The aquarium should be densely decorated with driftwood, rocks, and caves to break up lines of sight and provide hiding spots. If running a brackish tank, use salt-tolerant plants like Java Fern or Anubias, or opt for high-quality artificial plants.

Diet

The Figure 8 Puffer is strictly carnivorous. In the wild, they feed on benthic crustaceans and mollusks. In captivity, their diet must consist of hard-shelled foods such as small pond snails, ramshorn snails, small crabs, and clams. They will also readily accept meaty foods like frozen bloodworms, brine shrimp, and krill.

Some Feeding Tips

It is absolutely crucial to feed them hard-shelled foods regularly to naturally wear down their ever-growing teeth. If their teeth become too long, they will be unable to eat and may require manual trimming by a veterinarian. Avoid feeding them standard fish flakes or pellets, as they rarely accept them and they provide no dental benefits.

Breeding

Breeding the Figure 8 Pufferfish in a home aquarium is exceptionally difficult and extremely rare. They are egg layers that typically spawn on flat surfaces or plant leaves in the wild, but triggering this behavior in captivity has proven to be a major challenge for even the most experienced aquarists.

Conclusion

The Figure 8 Pufferfish is a delightful, personable, and visually striking pet that brings a lot of life to an aquarium. While their need for a specialized diet and specific water conditions makes them moderately challenging to care for, the reward of interacting with such an intelligent fish makes the extra effort completely worthwhile.