Otocinclus: tank size, group & compatibility data

Stocking notes

Small social grazers best added to established tanks with reliable biofilm and supplemental food.

For planning, StockingLab models Otocinclus at its approximate adult size rather than the juvenile size commonly seen in shops. That matters because space use and waste production can change dramatically as fish mature.

What the calculator checks

• Whether the tank's usable volume is below the 60 L / 15.9 US gal reference minimum.
• Whether the selected group is below the planner's typical 6 fish social starting point.
• Whether target temperature and pH sit inside the planning range.
• Whether prospective tankmates create predation, fin-nipping, territorial or water-overlap conflicts.
• Whether too many fish accumulate in the same bottom swim zone.

Before buying

Use this profile as a shortlist tool, not as a substitute for a dedicated care source. Confirm adult size, diet, sex ratio, habitat structure and locally relevant water conditions before purchase.

How to interpret this Otocinclus profile

At roughly 4.5 cm / 1.8 in adult length, Otocinclus should be planned at mature size rather than the smaller size commonly offered for sale. The reference tank is 60+ L / 15.9+ US gal, with a planning water window of 22–27°C and pH 5.5–7.5. A midpoint around 24.5°C and pH 6.5 is useful only as a comparison aid; the aim is stable water that overlaps the needs of the whole community.

The 6+ social starting point means tank size should be judged for the group, not for a single shop-sized fish. Its modeled waste factor is relatively modest at 0.55×, but that does not make the 60 L reference tank optional: swimming room, social structure and oxygen demand are separate constraints. Activity is modeled at 0.65×, but lower activity should not be mistaken for permission to compress the fish into an undersized footprint.

Common planning mistakes to avoid

• Keep the group at or above the 6+ planning starting point before adding extra species.
• Check that the planned temperature sits inside the shared 22–27°C range for every species in the community.
• Use the 60 L / 15.9 US gal reference as a starting point, then let actual tank dimensions, filtration and the full stock list refine the decision.

Bottom line: the profile is designed to screen a proposed aquarium for obvious pressure points. A result that passes StockingLab still needs to be checked against current, species-specific husbandry information for Otocinclus spp., especially diet, breeding behavior, sex ratio and habitat structure.