Before you add new fish, make sure your aquarium is fully cycled, with ammonia and nitrite at 0 ppm, stable temperature, pH, and salinity, and enough space for…
Stocking & Tank Management
Common Fish Compatibility Mistakes to Avoid
You’ll avoid most fish compatibility problems by matching temperament, adult size, water chemistry, and social needs, not just colors or juveniles. Don’t mix aggressive or territorial fish, like…
Stocking & Tank Management
What Fish Should Not Be Kept Together
You should not keep aggressive fish, fin nippers, predators, or fish with very different water needs together. Male bettas, cichlids, and some barbs can chase, bite, or bully…
Stocking & Tank Management
Aggressive Fish to Avoid in Community Tanks
You should avoid fish that nip fins, chase tankmates, or outgrow community tanks, because they can cause chronic stress, wounds, and infections. Tiger barbs, serpae tetras, some angelfish,…
Stocking & Tank Management
Peaceful Fish That Get Along With Others
If you want peaceful fish that get along with others, choose calm species like neon tetras, guppies, platies, corydoras, otocinclus, and kuhli loaches. You’ll get the best results…
Stocking & Tank Management
Best Community Fish for Freshwater Aquariums
For the best community fish in a freshwater aquarium, you should choose peaceful species that match in adult size, temperament, and water needs. Neon tetras, harlequin rasboras, and…
Stocking & Tank Management
Fish Compatibility Guide for Beginners
To choose compatible fish, you should match adult size, temperament, and water needs first. Keep tropical fish with tropical species, and align temperature, pH, and hardness as closely…
Stocking & Tank Management
What Fish Can Live Together in the Same Tank?
You can keep fish together safely when you match their adult size, temperament, diet, and water needs. Peaceful community fish like neon or cardinal tetras, rasboras, zebra danios,…
Stocking & Tank Management
How to Calculate Fish Capacity for Any Tank Size
To calculate fish capacity for any tank size, first find the tank’s actual water volume in liters or gallons, using its shape and subtracting displacement from substrate and…
Stocking & Tank Management
How Many Fish Can You Put in a 30-Gallon Tank?
In a 30-gallon tank, you can usually keep about 12 to 25 small adult fish, but you should stock by adult size, not juvenile count. A conservative ceiling…
Stocking & Tank Management
How Many Fish Can You Put in a 20-Gallon Tank?
You can usually keep about 8–12 small fish in a 20-gallon tank to start, but the real limit depends on adult size, bioload, behavior, and filtration. A 20-gallon…
Stocking & Tank Management
How Many Fish Can You Put in a 10-Gallon Tank?
You can usually keep about 7 to 8 inches of adult small, slim-bodied fish in a 10-gallon tank, not a full 10 inches. That rule is only a…
Stocking & Tank Management
How to Stock a Fish Tank the Right Way
You should stock a fish tank slowly, using each fish’s adult size, shape, and behavior instead of inch-per-gallon rules. Add no more than about 25% of the planned…