How to Choose Aquarium Fish

So you have set up your fancy home aquarium and it's looking great.  Air pumps  and filters  are connected, heaters  are working, and decorations  are situated perfectly.  The water has been cycled and you are all ready to add the best part!  However, selecting your aquarium inhabitants is much more complex than simply matching their colours. 

Remember the Rule of Thumb!

• No matter what kind of fish you select, a healthy aquarium should house one inch of fish per gallon of water! 
• Don't overcrowd your tank and keep in mind that some fish can grow quite large!

Freshwater Fish Types 

Fresh water fish are broken into two groups: cold water fish and tropical fish.  The two do not mix, so be sure to keep the fish from each category together based upon levels of aggression and compatibility.

Cold Water Fish

• Live best in fresh water around the temperature of 20º or even slightly lower.  
• Tend to grow very slowly, live longer, and are typically easier to care for than their tropical counterparts. 
• Will eat flake food .
• Should be kept away from home heaters and direct sunlight.

Cold Water Community Species
Barbs	Bloodfin Tetras	Goldfish	Guppies	Weather Loaches

Warm Water Fish

• Like water temperatures between 25-26º.
• Need an aquarium heater  and thermometer  for tracking a consistency.
• Can be very fickle with one another and should be monitored for compatibility.

This warm water gang is compatible, but don't mix them with any others!
Neon Tetras	Harlequin Rasboras	Ghost Shrimp	Glass Fish	Honey Gouramis

Live best in schools, with their own kind.
Danios	Swordtails	Mollies	Platies	Bigger Tetras

Aggressive, yet a perfect mix for each other.
Freshwater Angels	Dwarf Gouramis	Neon Blue Gouramis	Neon Blue Rainbows	Plecostomus Catfish

Cichlids

• A special group of very aggressive, warm freshwater fish, mostly African and Neotropical.
• Pronounced "sick-lid."
• Should NEVER be mixed with any other kids of fish!
• Should be kept in groups with many others of their kind, so as not to become overly aggressive.
• Have "personalities" and can be seen digging, protecting their territory, and nurturing their young.
• Will eat floating pellet food .
• Will grow tremendously within a year and should then be moved to a much larger tank .

New World Cichlids
Firemouth	Convict	Texas Cichlid	Jack Dempsey	Green Terror

Mbuna Cichlids
Auratus	Kenyi	Red Zebra	Pindani	Johanni

Saltwater Fish Types

Saltwater fish  are often difficult to care for and can be tricky to match up.

Predatory 

Remember that any fish larger than other fish will probably perceive the smaller ones as prey.  It is best to keep fish that are more aggressive and predatory in a tank with one another.  

A predatory tank community should be left to these species only!
Lionfish	Grouper	Hawkfish	Snapper	Triggerfish

Protectors

Many species will work well together, but are protective of their species in the opposite sex.  It is best to limit your tank to one couple per species, or just one species per tank to avoid this complication.  Adding a third of any species can only equal trouble.

Though possessive, they still play well with others.
Clownfish	Butterflyfish	Boxfish	Angelfish	Damselfish

Related Guides

See some of our other guides for information on fish care and aquarium equipment.

• Aquarium Filters and Pumps
• Aquatic Plants 
• Freshwater Aquarium Basics
• Saltwater Aquarium Basics
• Tropical Fish Care