About FishPicker

FishPicker is a free tool for planning a freshwater aquarium. You choose a tank and some fish, and it tells you whether they can live together before you spend any money.

How the checks work

• Temperature and pH. Each species has a range. Fish can share a tank only if every range overlaps.
• Tank size. Each species has a minimum tank, based on its adult size and how much it swims.
• Group size. Schooling fish are flagged when there are too few of them.
• Behaviour. Each species is tagged with what it does: nips fins, guards territory, hunts smaller fish, eats shrimp or snails. Two species are flagged when one's habits put the other at risk. A list of known problem pairings covers the cases a general rule misses.
• Stocking. Each species is weighted by how much waste an adult produces. The total is compared with the tank's volume in gallons. Choosing heavy filtration in the planner raises that limit by 20%, and light filtration lowers it by 20%. These are rules of thumb, not measurements.
• Water changes. The weekly water change the planner suggests rises with stocking: 20% for a lightly stocked tank, up to 50% for an overstocked one. This is also a rule of thumb.

What it cannot tell you

Individual fish differ. Some bettas tolerate tank mates and some attack everything. Care ranges also vary between sources and between wild and tank-bred fish. Treat a "yes" as a good starting point, watch new fish closely, and check with your seller.

The checks cover the 100 animals and 14 plants listed on this site. A pairing that is not flagged has passed these checks. That is not a guarantee.

Images

The fish and plant images are AI-generated illustrations. They show typical colouring and shape, and they are not photographs of real animals.