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What is a cool fish to have?

What is a cool fish to have?

When choosing a cool fish for an aquarium, there are many options to consider. Some of the most popular “cool” fish include bettas, goldfish, angelfish, discus, clownfish, guppies, tetra, oscars, and more. The right fish depends on your tank size, water parameters, tank mates, and personal preferences. In this article, we will discuss different types of cool freshwater and saltwater fish to help you decide which one is best for you.

Betta Fish

Betta fish, also known as Siamese fighting fish, are one of the most popular fish for aquariums. Here are some key points about betta fish:

– Bettas come in vibrant colors like red, blue, green, white and black. The flowing fins of male betta fish make them look beautiful as they swim around the tank.

– They are labyrinth fish, meaning they can breathe atmospheric oxygen using a special organ called the labyrinth. This allows them to thrive in low oxygen environments.

– Bettas prefer to live alone. Male bettas will fight with other male bettas and may nip at fins of fish like guppies. For this reason, they’re best kept alone in a 5 gallon or larger heated and filtered tank.

– With proper care, betta fish can live 3-5 years. They need water in the 78-80°F range and should be fed a varied diet of betta pellets and frozen or freeze-dried foods like bloodworms. Weekly water changes are a must.

– There are also long-finned betta breeds like halfmoon and crowntail bettas. Their big, showy fins make them a beautiful highlight of any aquarium when given enough swimming space.

So in summary, bettas are a popular fish for beginners because of their hardiness, personality, bright colors and flowing fins. As long as they are kept properly, they make an interesting addition to nano tanks and other aquarium setups.


Here’s a quick overview of goldfish as a cool fish for aquariums:

– Goldfish come in many varieties like common, comet, fantail, shubunkin, oranda and ranchu. They have bright orange, yellow, white, black or mottled coloration.

– They can grow quite large, up to 10-12 inches for single tailed types and 6 inches for fancy varieties. Goldfish need at least 20 gallons for the first fish and 10 extra gallons for each additional fish.

– Goldfish are coldwater fish, meaning they thrive in unheated aquariums around 65-75°F. A filter is required since goldfish are messy!

– Given proper space, goldfish can live up to 10-15 years. They eat flake foods, pellets and also enjoy live, frozen or freeze-dried treats like bloodworms and brine shrimp.

– Goldfish have upbeat, social personalities. They coexist well with similar sized goldfish but should not be kept with tropical community fish due to different temperature needs.

– Fancy goldfish with bubble eyes, celestial eyes or long flowing fins may be vulnerable to nippy tankmates. Stick to other peaceful goldfish.

So in summary, goldfish are classic fish that come in many colors and sizes. When given a large filtered tank, they are interesting, long-lived pets for aquarists of all levels.

Freshwater Angelfish

Angelfish are a popular cichlid known for their unique shape. Here’s an overview as a cool freshwater fish:

– Angelfish have compressed, tall bodies and long flowing fins. Selective breeding has produced angelfish in black, silver, gold, marble, and other color patterns.

– They grow up to 6 inches tall and require at least a 20 gallon tank. A planted aquarium with driftwood and caves suits them well.

– Angelfish prefer water around 76-82°F and appreciate low to moderate water movement. Weekly 25% water changes are ideal.

– They are omnivorous and eat flakes, pellets, frozen or freeze-dried foods like brine shrimp and bloodworms.

– Angelfish are shoaling fish, so it’s best to keep at least six together. They can be aggressive toward fish with similar body shapes. Avoid keeping them with guppies or neon tetras that may be mistaken as prey.

– Their unique shape and graceful movements make angelfish an interesting focal point in community tanks. Under suitable conditions, they can live up to 10 years.

So in summary, angelfish are a rewarding fish for intermediate aquarists. Given their specific needs, they do best in established tropical community aquariums with compatible tank mates.

Discus Fish

Here’s an overview of discus fish as advanced but rewarding aquarium inhabitants:

– Discus fish have flat, rounded bodies in vibrant red, blue, green and brown color variations. Some varieties have bright blue or red eyes.

– They grow around 6 inches in diameter and need at least a 30 gallon tank with very warm, clean water around 82-86°F.

– Discus prefer a stable pH around 6.0-7.0. They are sensitive to water quality and need frequent testing and partial water changes. A cycled tank is mandatory.

– Discus are shoaling fish and should be kept in groups of at least 5-6. They can be timid and may not eat without companions.

– They eat a varied, meaty diet including beefheart, flakes, pellets and frozen foods like bloodworms and brine shrimp.

– Discus thrive in planted tanks with driftwood and rock formations. Dim lighting and a sandy substrate help them feel secure.

– With excellent care, discus can live up to 10 years. Their stunning colors and graceful movements make them a standout aquarium fish for dedicated hobbyists.

In summary, discus require specialized tank conditions but their beauty and interesting behaviors make them rewarding for experienced fishkeepers. They do best in species-only tanks.


Here’s an overview of clownfish, a popular saltwater fish for reef tanks:

– Clownfish are orange, black, and white in color with thick black bands around their bodies. Popular species include common, tomato, and false percula clownfish.

– They grow up to 4 inches long and do well in 30+ gallon reef tanks with plenty of hiding places. They prefer water temps from 74-80°F.

– Clownfish form symbiotic relationships with anemones like bubble tip and carpet anemones. The anemone offers protection while the clownfish deters predators.

– Clownfish are omnivores, eating meaty foods including mysis shrimp, brine shrimp, spirulina and quality flakes. Feed 2-3 small meals daily.

– They are social and normally live in groups with a hierarchy of dominant females, males and juveniles. Introduction should be done with caution.

– With proper care including stable water quality, a varied diet and compatible tank mates, clownfish can live up to 10 years.

In summary, clownfish are classic reef inhabitants thanks to their bright colors, playful personalities and symbiotic anemone relationships. Their ease of care makes them ideal for beginner marine aquarists.


Here’s a quick rundown of guppies as a fun and active nano fish species for community tanks:

– Guppies are livebearers, meaning females give birth to free-swimming fry instead of laying eggs. They will breed prolifically if both sexes are present.

– Male guppies are brightly colored, with elaborate tails in hues like red, yellow, blue, purple and black. Females are more subdued in color.

– Guppies only grow to around 1-2 inches total length, so they are well-suited to nano tanks starting around 5 gallons. They prefer water temps around 74-82°F.

– Given their small size, tank decor like plants, rocks and driftwood should have smooth edges to avoid injuring their flowing tails and fins.

– Guppies are peaceful community fish when kept with similarly sized tankmates. Avoid large or aggressive species that could eat them.

– They are omnivores and will accept a varied diet of flakes, pellets, live or frozen foods like bloodworms, brine shrimp and insect larvae.

In summary, guppies are active, colorful nano fish that breed readily. When given proper tank conditions, they can live 2-3 years and entertain both beginner and experienced aquarists.

Tetra Fish

Here’s a quick overview of tetra fish as cool freshwater species for community tanks:

– Tetra fish comprise many popular aquarium species including neon, black neon, ember, congo, lemon, rummy nose, emperor and more.

– They come in different colors and fin shapes, but most have long, slender bodies ideal for moving around planted tanks. Tetras grow around 1-2 inches long depending on species.

– Tetras are peaceful schooling fish. Most varieties should be kept in groups of 6 or more of their own species to feel secure and exhibit natural behaviors.

– They do well in 10+ gallon planted tanks with subdued lighting and plenty of hiding spots. Water temperature ideal range is 72-82°F depending on species.

– Tetras feed on live, frozen and flake foods in the aquarium. Variety is important, including brine shrimp, bloodworms, daphnia, and high quality flakes. They are sensitive to poor diets.

– With high water quality and proper diet, tetra species like neon and cardinal tetra can live 5+ years. Their bright colors and active movement make them excellent community fish.

In summary, tetra fish are diverse, hardy, and colorful schooling fish perfect for small-to-medium community aquariums. There’s a tetra variety suitable for any peaceful tropical setup.

Oscar Fish

Here are some quick facts about oscar fish as unique freshwater aquarium residents:

– Oscars have an oval-shaped body and long fins. Common varieties include albino oscars, tiger oscars, and red oscars with vibrant orange-red coloration.

– They grow very large, up to 12 inches in length. Oscars need a minimum 75 gallon aquarium, along with efficient filtration and weekly water changes.

– Oscars prefer warm water from 75-81°F and a pH close to neutral. A smooth substrate is recommended so they don’t damage their ventral fins.

– Oscars are carnivorous and will readily accept foods like shrimp, pellets, massivore diet, and occasional treats like live fish or earthworms. They are voracious eaters.

– Despite their size, oscars are generally peaceful when provided with sufficient aquarium space. Some may eat small tank mates or nip fins of others. Avoid crowded tanks.

– Their intelligence and personality make oscars an interactive fish. With a commitment to tank size and water quality, they can live 8-12 years in captivity.

So in summary, oscar fish are a stunning yet demanding cichlid. Their appetite and size means they are only suitable for very large tanks with no small tankmates. But their beauty and charm is worth it for experienced aquarists.

Choosing the Right Fish for You

When selecting a cool fish for your aquarium, there are many important factors to consider:

– Tank size – Make sure the fish you choose will have adequate room to thrive, based on its adult size. Avoid overstocking.

– Water parameters – Fish have optimal temperature, pH and hardness ranges. Choose fish compatible with your tank water.

– Temperament – Mix aggressive species with caution. Choose peaceful community fish or keep species-only tanks according to temperament.

– Care difficulty – Beginners should start with hardy fish before trying advanced species like discus. Match fish to your experience level.

– Cost – Larger and more exotic fish often have a higher price tag. Factor costs for equipment and ongoing care too.

– Time commitment – Some fish require more frequent tank maintenance and care. Make sure you can provide consistent upkeep.

Researching fish species in depth and shopping at a reputable aquarium store are key to matching fish to your tank and lifestyle. Don’t be afraid to ask questions to ensure your fish choice is a good fit!


When it comes to choosing a cool fish for an aquarium, there are many options like bettas, goldfish, angelfish, clownfish, tetras, oscars, and more. Each fish has specific care needs, so it’s essential to match the right fish to your tank size, water parameters, experience level, tankmates and maintenance commitment. With some research and preparation for their required care, any of these fish species can make a stunning and rewarding aquarium resident. A suitable fish for one hobbyist may not work for another, but that’s part of the fun – picking your perfect finned friend!