Midas Blenny Tank Size Guide
The Midas Blenny is a larger, more active blenny than most nano-reef staples. Tank size planning matters more for this species than for smaller blennies like the Tailspot, both because of its adult size and its territorial tendencies toward similar fish.
Minimum Tank Size
A 30-gallon tank is the workable minimum for a single Midas Blenny. The fish reaches 4–5 inches and is an active swimmer that uses both rockwork and the mid-water column. Tanks smaller than 30 gallons are not recommended — the fish will be cramped and territorial behavior toward tankmates is more likely in confined spaces.
Recommended Tank Size
A 40-gallon or larger tank is preferred for a Midas Blenny in a community reef. This provides adequate swimming space, sufficient rockwork for territory, and room for other species without crowding. A 40-gallon breeder footprint is well suited to a Midas Blenny alongside a small community of peaceful reef fish.
Tank Size and Territory
Midas Blennies can be territorial toward other blennies and similarly shaped fish. In smaller tanks, this territorial behavior is more pronounced because the fish cannot establish separate zones. In a 75-gallon or larger tank with ample rockwork, a Midas Blenny and a Tailspot Blenny can sometimes coexist — but this is not guaranteed and requires monitoring.
→ Midas Blenny vs Tailspot Blenny
Tank Size by Community Configuration
- 30 gallons: Single Midas Blenny with 1–2 other small peaceful species (clownfish, firefish, cardinalfish). Workable but tight.
- 40–55 gallons: Midas Blenny with a full small community reef — clownfish, cardinalfish, watchman goby. Comfortable for all species.
- 75+ gallons: Full community with multiple species across all niches. Room for a second blenny species if desired, with careful monitoring.