Meet the Rainbowfish
Make your freshwater aquarium more colorful by caring for the beautiful members of the rainbowfish family.

If you've ever found yourself entranced by a riot of color in a pet store aquarium, chances are that you were looking at a tankful of rainbowfish. These sociable freshwater fish can do well in a variety of conditions, making them ideal for first-time fish owners or anyone looking for a relatively trouble-free pet. However, you still need to understand this fish's basic needs and recognize potential health concerns that might merit a trip to the vet. Here's an enlightening introduction to the world of rainbowfish.
Meet the Rainbowfish
The term "rainbowfish" actually applies to many species within the family Melanotaeniidae. These species are native to places like Madagascar, Australia, Indonesia, and Papua New Guinea. The most popular species, and the ones you're most likely to find at your local pet store, include the Boesman's rainbowfish, the black-banded rainbowfish, and the goldie rainbowfish. These fish average four to five inches in length and often live for eight or more years (with larger ones living longer than smaller ones).
True to their collective name, rainbowfish can dazzle you with the range and vividness of their colors. You'll find these freshwater fish sporting shades and gradations of orange, green, black, red, blue-grey, teal, and yellow. Rainbowfish also have upper and lower dorsal fins, big eyes, and appear almost "flat" or two-dimensional when viewed from the front.
A Healthy Rainbowfish Environment
Rainbowfish like to keep active, so you'll want to give them plenty of swimming room. Although you might get away with a 15-gallon tank if you own just half a dozen small rainbowfish, a 30-gallon tank will serve your purposes much better if you plan to keep more (or larger) fish. Make sure to place a lid on top of the tank to prevent these sprightly pets from jumping out of the tank. You can also enliven your rainbowfish tank with rocks, plants, and hiding places.
You shouldn't have much trouble providing the right water and temperature for your rainbowfish. A temperature range of 74 to 80 degrees Fahrenheit will keep them comfortable, while a relatively neutral pH range of 6.5 to 8 will help ensure their health. Once a week, siphon 25 percent of the water out of the bottom of the tank, replacing it with fresh water.
What to Feed Your Rainbowfish
As omnivores, rainbowfish can live on a combination of plant and animal foods, including ordinary store-bought fish flakes. But to provide optimal health and to get the brightest colors out of your fish, rotate this diet with the kinds of foods they'd eat in the wild. Every couple of days, feed your rainbowfish live prey such as mosquito larvae, glassworms, and bloodworms.
Don't overfeed your rainbowfish. Administer the food carefully, in amounts that your pets can consume within just two to three minutes. Three of these small daily feedings will give them all the nutrition they need to stay healthy.
Interactions With Other Fish
Rainbowfish qualify as community fish, meaning that they can happily share a tank with other peaceful-minded fish such as catfish, guppies, pygmy rasboras, and tetras. If you already have fish and you're not sure whether they'll get along with some new rainbowfish, check with your pet store or exotic animal vet before you add them to a populated environment.
When you're ready to buy a rainbowfish, you should make up your mind to buy six or more at one time. Rainbowfish thrive on each other's company; in fact, if you add females to your tank, the males will go to a lot of trouble to show off their colors to them! Just make sure you always have more females than males in the same tank so the males will have less cause to get aggressive with their fellow males.
When to Consult Your Exotic Pet Vet
Despite their inherent hardiness, rainbowfish can still get sick from dietary insufficiencies, poor water quality, and other issues that may be harder to pinpoint. Examples of diseases afflicting rainbowfish include fin rot, cottonmouth, fungal infections, a parasitic condition called ich, and a skin-peeling disease known as velvet.
While some of these conditions may sound pretty esoteric, you can usually spot the symptoms of a rainbowfish health problem. Watch for:
- Loss of appetite
- Unusually rapid gill motion
- Fading colors
- Ragged-looking fins
- Elevated scales
- White spots
- Changes in eye appearance
If you notice such changes in your rainbowfish, or you see other inexplicable changes in their appearance of behavior, schedule an appointment with a veterinarian. Choose a veterinary clinic that specializes in care for fish and other exotic animals. If you can't find such a specialist in your area, try a regular vet or take your concerns to the pet store.
Home care may be sufficient to stop and/or reverse some of these health challenges. For instance, adding aquarium salts to your water, adjusting the water's pH, or cleaning the water may help treat a variety of issues. However, you may also need prescription antibiotics. You can find commercially available ich remedies.
Learn by Doing -- and by Consulting the Experts
You can learn a lot by keeping rainbowfish, giving you a knowledge base that will help you raise more challenging species down the road. Along the way, make all the connections you can with experienced rainbowfish owners, pet store personnel, and exotic animal veterinarians!
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