80L Aquarium with Mollies (4) + Pygmy Corydoras (8) - Active Community Setup

A 80-liter aquarium makes for a solid size for a beginning community tank, as it is big enough to keep the water stable while still being easily serviceable at home. This predefined aquarium combines 4 Mollies (Poecilia sphenops) with 8 Pygmy Corydoras (Corydoras pygmaeus) in a mix that will give you movement in the midwater and gentle bottom activity in a compact setup.

This preset is designed to be practical: hardy fish, easy feeding, and a straightforward aquascape that allows for stable water quality.

Why this stocking works in a 80L tank

Mollies are active livebearers. They’re interactive, always moving, and they give a tank that “busy aquarium” feel. Pygmy corydoras balance that activity by adding peaceful foraging behavior near the bottom and lower water column.

A 80L tank helps because livebearers can be “messier” than many nano fish. The extra water volume makes it easier to keep parameters stable, especially when you stick to a simple weekly routine.

Important note about group sizes (and why you may want to increase cory count)

Pygmy corydoras are social fish and generally do best in larger groups. This preset uses 4 as a starting point to fit the 80L community concept, but if you want the most natural cory behavior, consider increasing them when possible (and adjusting stocking accordingly). A larger group usually means:

• bolder behavior (less hiding)
• more natural shoaling and foraging
• a more interesting “bottom layer” to watch

If your Virtual Aquarium tool shows a higher minimum group size for pygmy corys, treat this preset as a “starter community,” and use the tool to tune it to your preferred group-size rule.

Best tank layout for mollies + pygmy corydoras

This combination does best with a planted layout that leaves open swimming space:

• Open midwater area for mollies to cruise
• Plant cover along the sides/back to reduce stress and create territories
• Sand substrate (highly recommended for corydoras comfort and natural foraging)
• Optional floating plants to soften light and help fish feel secure

Mollies also appreciate visual breaks (plants/wood) so chasing doesn’t focus on one fish.

Filtration and flow

For livebearers, clean water and oxygenation are key:

• choose a filter that provides steady circulation
• avoid extreme flow that keeps fish pinned in one area
• ensure good biological filtration capacity (stability matters more than power)

If you notice debris collecting, adjust flow direction or add a small pre-filter sponge to improve overall water cleanliness.

Maintenance routine (simple and reliable)

For a 80L livebearer community, consistency prevents most problems:

• Cycle the aquarium first (ammonia/nitrite must be 0)
• 25–30% weekly water change as a baseline
• light substrate cleaning where waste collects (don’t over-clean planted zones)
• rinse filter media in old tank water when flow drops

Mollies can produce more waste than many small schooling fish, so weekly water changes keep everything stable and algae under control.

Feeding tips

Keep feeding clean and predictable:

• mollies: quality flakes/pellets + occasional veggie-based foods
• pygmy corydoras: small sinking foods (micro wafers/pellets) after lights dim, so they get their share
• avoid overfeeding; in smaller tanks, extra food quickly becomes extra waste

A good method is a small daytime feed for mollies and a small sinking portion for corys later.

Customize this preset in Virtual Aquarium

Open this predefined aquarium in our Virtual Aquarium tool to:

• adjust fish counts and instantly see updated required water volume
• increase the pygmy cory group to match your preferred minimum group rule
• check the combined suitable temperature range for the selected community
• try alternatives (platies instead of mollies, different cory counts, etc.)

This preset is a strong starting point for an active 80L tank-especially if you keep it planted, feed lightly, and stick to weekly maintenance.