How many fish in a 60-litre aquarium? The realistic calculation
The 60-litre tank is the best-selling starter size, and it is also the one beginners overstock fastest. The question "how many fish?" has no single answer: it all depends on the species, its adult size, and the organic load it produces. A study by Toby Ellis and colleagues, published in 2002 in the Journal of Fish Biology, demonstrated the direct relationship between stocking density and welfare in fish, with water quality and behaviour deteriorating beyond a certain threshold (study on Google Scholar). All our setup guides are gathered in the tanks and habitats section.
Why the "1 cm of fish per litre" rule is misleading
The old rule of one centimetre of fish per litre gives a first idea but greatly overestimates real capacity. A 60-litre aquarium loses 8 to 12 litres to substrate, decor, and unfiltered volume, so you actually work with about 50 usable litres. More importantly, a fish twice as long does not pollute twice as much but far more, because mass and therefore waste output rise exponentially with size.
The real limiting factor: organic load
What caps the population is not swimming room, it is the ability of the filter and bacteria to process ammonia. A freshly cycled tank, as explained in our guide to setting up a 60-litre freshwater aquarium, only supports a few fish at first. You add stock gradually, in small batches two to three weeks apart, watching your parameters.
Examples of a balanced 60-litre community
- A school of small fish: 8 to 10 neon tetras or 8 rasboras, plus a small cleanup crew (6 dwarf corydoras or a few shrimp).
- A featured pair: 6 guppies or platies with 6 corydoras, bearing in mind that livebearers breed quickly.
- A solo tank: a single betta surrounded by shrimp and snails makes perfect use of this volume with no overstocking risk.
Conversely, the goldfish, the adult angelfish, or any bulky cichlid have no place in 60 litres: their adult size and needs exceed this format, as our article on feeding angelfish points out.
How do I know if my tank is overstocked?
Fish hanging at the surface gulping air, ammonia or nitrite spikes on your tests, water that clouds quickly after each feeding: these are the warning signs. The general principle of the calculation is detailed in our guide how many fish in an aquarium, to be adapted to your actual volume.
Frequently asked questions
Can I keep a goldfish in 60 litres?
No, a goldfish produces a huge amount of waste and reaches 20 cm or more: it needs at least 80 to 100 litres per individual, ideally a pond. The 60-litre suits small tropical species.
Is it better to have many small fish or a few large ones?
Several small schooling fish use the space better while polluting little, whereas a single large fish quickly saturates filtration. In 60 litres, the first option gives a livelier, more stable aquarium.
Do shrimp count toward the population?
Their organic load is negligible compared with fish, so you can add them generously without raising the count. Find all our guides on the aquarium hub.
This guide is part of Planète Pets’s Fishkeeping universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.