Figure 8 Puffer (Dichotomyctere ocellatus)

Species Overview The Figure 8 Puffer (Dichotomyctere ocellatus) is one of the most recognizable small puffers in the aquarium hobby, named for the looping black markings across its back that often resemble the number eight. Its bright yellow-green coloration, bold patterning, constantly moving eyes, and unusual swimming style give this fish an incredible amount of personality for its size. You may also recognize this species by its older scientific name, Tetraodon biocellatus, which is still commonly used throughout the aquarium trade. What really makes the Figure 8 Puffer special, though, is its behavior. These are intelligent, curious fish that spend much of the day inspecting rocks, wood, substrate, and anything else that changes within their environment. Many quickly learn where food comes from and will begin following their keeper along the aquarium glass at feeding time. It's difficult to keep one for very long without beginning to recognize its individual habits and personality. The Figure 8 Puffer is best suited to an aquarist who wants to build an aquarium around the needs of the fish rather than simply add another species to an existing community. Proper salinity, excellent water quality, a thoughtfully structured environment, and a diet that includes hard-shelled foods are important parts of long-term care. For the aquarist willing to provide those things, few freshwater or brackish aquarium fish offer quite the same combination of intelligence, curiosity, and personality. What We Love About This Fish Huge personality in a small fish – Figure 8 Puffers are intelligent, observant, and constantly investigating their surroundings. Unmistakable patterning – Yellow-green coloration and looping black markings give every Figure 8 Puffer a slightly different appearance. Fascinating feeding behavior – Watching a Figure 8 Puffer hunt snails, crustaceans, and other hard-shelled foods is one of the most interesting parts of keeping the species. Quick Care Guide Care Level: Intermediate Temperament: Semi-Aggressive; may be territorial and prone to fin-nipping Diet: Carnivorous; snails, crustaceans, mollusks, frozen foods, and other meaty foods Source: Collected Average Adult Size: Approximately 3 inches (7.5 cm) Average Purchase Size: Approximately 1–2 inches (2.5–5 cm) Minimum Aquarium Size: 20 gallons for a single adult; additional space is required when attempting to maintain more than one Tank Level: All Levels Activity Level: Active Social Classification: Best maintained individually or in a carefully planned species-focused aquarium Shrimp Safe: No Plant Safe: Generally, although brackish conditions significantly limit suitable plant choices Special Requirement: Hard-shelled foods should be included regularly to help manage continuously growing teeth Recommended Water Parameters Temperature: 75–82°F (24–28°C) pH: 7.0–8.0 General Hardness (GH): 8–20 dGH Carbonate Hardness (KH): 6–15 dKH Salinity: Fresh to low-end brackish; stable low-end brackish conditions are commonly recommended for long-term aquarium care Specific Gravity: Approximately 1.002–1.005 when maintained as a low-end brackish aquarium A Note About Freshwater vs. Brackish Water This is one of the most confusing parts of Figure 8 Puffer care because you'll find them described online as both freshwater and brackish fish. There is a reason for that. Dichotomyctere ocellatus occurs naturally in environments influenced by both fresh and brackish water, and specimens can tolerate a range of salinities. For long-term aquarium care, we recommend maintaining Figure 8 Puffers in stable low-end brackish conditions rather than treating them as conventional freshwater community fish. Marine salt mix should be used to create brackish water, and salinity should be measured rather than estimated by simply adding aquarium salt. Stability and water quality matter more than constantly changing salinity in an attempt to imitate tidal conditions. Figure 8 Puffers are also messy eaters and are sensitive to deteriorating water quality. Strong biological filtration, good oxygenation, regular water changes, and a fully cycled aquarium are especially important. Their relatively small adult size should never be mistaken for low waste production or low maintenance.