Rainbowfish are a popular choice for aquarium enthusiasts due to their vibrant colors and relatively easy care. The term "rainbowfish" applies to many species within the family Melanotaeniidae. These fish are native to Australia, Papua New Guinea, parts of Indonesia and Madagascar, where they are found in streams, rivers, lakes, and swamps. Most rainbowfish available in the hobby are commercially produced on farms in Southeast Asia and Florida. This article provides a comprehensive guide to rainbowfish diet and care, covering various aspects from their natural habitat to breeding.
Rainbowfish Species and Groups
Aptly named Rainbowfish are made up of two main groups. The first group contains the Families Melanotaeniidae and Bedotiidae, which include larger, active fish in the genera Melanotaenia, Glossolepis and Bedotia, like the Madagascar Rainbow. (An exception is the tiny Threadfin Rainbow, I. werneri, which should be treated like a Pseudomugilid.) The second group includes the Families Pseudomugilidae and Telmatherinidae. Pseudomugilidae is comprised of smaller, more docile fish, often referred to as "Blue Eyes". The Family Telmatherinidae includes a lone species, Marosatherina ladegesi, the Celebese Rainbow. It is not hard to understand how rainbowfish get their name once you see a school of brilliantly colored, adult Melanotaeniids or a pair of "Blue Eyes" in full spawning dress.
Natural Habitat and Conservation
Rainbowfish are native to Australia, Papua New Guinea, and parts of Indonesia, where they are found in streams, rivers, lakes, and swamps. Some wild rainbowfish populations have become threatened by human activity, as well as the introduction of invasive species. Most rainbowfish available in the hobby are produced commercially on farms in Southeast Asia and Florida.
Water Requirements
Many Melanotaeniids come from hard, alkaline water, but captive bred fish available today will thrive in a wide range of water conditions. They do best between 74° and 78° F, at a pH of 7.0 to 8.0 and alkalinity between 5° and 20° dKH (90 ppm to 360 ppm). Madagascar Rainbows come from more acidic water and should be kept between 74° and 80°F, pH of 6.5 to 7.5 and alkalinity between 3° and 14°dKH (55 ppm to 250 ppm). Pseudomugilids prefer temperatures between 76° and 82° F, pH of 6.5 to 7.5 and alkalinity between 5° and 10° dKH (90 ppm to 180 ppm). If the aquarium is kept in a room below 74° F, use an Aqueon Aquarium Heater to maintain the correct temperature. Maintain good filtration and do a 10% water exchange every week or 25% every 2 weeks using an Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner. Don't forget to treat tap water with Aqueon Water Conditioner before refilling your aquarium!
Water Parameters for Different Rainbowfish Species
| Species Group | Temperature (°F) | pH | Alkalinity (dKH) |
|---|---|---|---|
| Melanotaeniids | 74-78 | 7.0-8.0 | 5-20 |
| Madagascar Rainbows | 74-80 | 6.5-7.5 | 3-14 |
| Pseudomugilids | 76-82 | 6.5-7.5 | 5-10 |
Housing Requirements
Melanotaeniids are active fish and need plenty of swimming space. Smaller species like the Neon Dwarf Rainbow (Melanotaenia. praecox) and the Celebese Rainbow (M. ladegesi), will thrive in a 30-gallon aquarium, whereas most other Melanotaeniid rainbowfish need an aquarium of at least 50 gallons or larger. Adequate cover in the form of tall plants and other structures is important, but open swimming areas should be provided as well. The "Blue Eyes" and Threadfin Rainbows are perfectly happy in community aquariums of 20 gallons or well-planted species tanks of 10 gallons or less.
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An appropriate tank size is very important to guarantee the happiness of your fish. Since Rainbowfish may vary slightly in terms of size, you need to research all relevant information about the specimen you intend to keep beforehand. Most Rainbowfish species prefer long tanks. It allows them to have plenty of space to swim and shoal in groups. Small specimens may fit into a 10-gallon tank, whereas the larger specimens require a bigger tank to survive. For example, Boeseman or Duboulay will need at least a 20-gallon tank, while Red and Sepik Rainbowfish can comfortably be kept in a 40-gallon aquarium. However, like we discussed above, Rainbowfish tend to be active and love swimming.
Aquarium Setup
Once the aquarium is decided, the next step is water parameters. Their wild habitats are lakes, rivers, streams, and swamps, which share the common features of slightly alkaline and hard water, with lots of plants. Most captive-bred Rainbowfish can adapt to a wide range of water conditions. Despite that, there is still a standard for each specific species. The Melanotaeniidae branch would be happy to be splashed in fairly warm water of 74° - 78° F (23.3°- 25.6° C) with pH levels ranging from 7.0 to 8.0 and KH between 5° and 20° dKH. Similar parameters are applied to Telmatherinidae (Sulawesi) with a few adjustments. Bedotiidae and Pseudomugilidae are on the other hand. They are more contended with relatively acidic environments and cooler water. You will see Bedotiidae find its comfort in the temperature range of 74° - 80°F (23.3°-26.7°C), a pH of 6.5 to 7.5, and alkalinity between 3° and 14°dKH. Considering the above, you may need a heater if the room housing Rainbowfish tanks has temperatures lower than 74° F.
Plants and Decorations
Rainbowfish tanks cannot lack live aquatic plants. Although the species is regarded as an omnivore, they could live in harmony with hard-leaved plants. Some potential candidates you can consider are Stargrass, Glosso, Hygro polyspherma, Duckweed, Hygrophila corymbosa compact, and Java fern.
Behavior and Compatibility
Melanotaeniid rainbowfish are peaceful yet active and get along with most similarly sized, non-aggressive fish. Different species can be mixed together and can also be kept with larger tetras, peaceful barbs, rasboras, danios, catfish and even non-aggressive cichlids such as Kribensis. Rainbowfish are shoalers and should be kept in groups of 6 or more for best effect. Males will exhibit their best colors as they vie for attention from females. Pseudomugilids and Threadfin Rainbows are docile and sometimes shy, so tank mates should be chosen carefully. These may include pygmy rasboras, small tetras, peaceful barbs, Otocinclus and Corydoras catfish. Always consult an aquarium expert before buying any new fish for your aquarium.
Rainbowfish is one of many freshwater species that possesses both beauty and a nice personality. They are resilient, peaceful, sociable, semi-aggressive (mostly when mating season), and active. They love swimming and are fast swimmers, sometimes capable jumpers. A tight lid is indispensable for Rainbowfish aquariums. They occasionally jump out of water when threatened or scared.
Read also: Learn about Rainbow Scarab Beetle Feeding
Suitable Tank Mates
The answer is yes, so long as other species are of comparable size and temperament. Most aquarists even advised that you house them with the “fast-swimmers” as Rainbowfish tends to make slower-swimming fish feel uncomfortable and anxious with their talent. It is worth noting that Rainbowfish is a shoaling species. Hence, you need to keep them in groups so they can thrive and be more active.
Suitable tankmates for Eastern Rainbowfish include tetras, peaceful barbs, Corydoras catfish, and other rainbowfish species. Avoid housing them with aggressive or overly large fish that may intimidate them.
Diet and Feeding
Rainbowfish are omnivores and need both vegetable matter and meat-based foods in their diet. Melanotaeniids will thrive on Aqueon Tropical Flakes, Color Flakes, Spirulina Flakes and Betta Treat. Pseudomugilids will accept these foods as well, but may require a higher proportion of frozen and even live foods to promote optimum health and color. For best results, rotate your fishes' diet daily and feed only what they can consume in under 2 minutes, once or twice a day.
Like keeping other fish, providing and maintaining a balanced and nutrient-sufficient diet is essential to keep your Rainbowfish healthy and robust. Rainbowfish are omnivorous; therefore, they require a good combination of ‘green’ matter and high-protein foods. Try to rotate the menu items to stimulate their appetite and ensure a variety of nutritional sources. A good rule of thumb is to feed your fish a sufficient amount so they can consume within 2-3 minutes. Be careful since Rainbowfish is a surface feeder, they won’t likely eat those foods sinking to the bottom of the tank.
When maintained properly, most of the commonly-kept Rainbowfishes eagerly gobble up just about any food that comes their way. Moths, crane flies, beetles and others can easily be collected around outdoor lights, and a variety of commercial and home-made traps are very effective. Sweeping a net through tall grass will quickly yield a vast assortment of leaf hoppers, ants, flies and other tiny insects (all fascinating in their own right). Larger insects can be frozen and crushed prior to use. Canned invertebrates marketed for captive reptiles offer an excellent means of supplementing the diets of Rainbowfishes (I rinse well before using). Zoo Med’s Canned Shrimp is one of the few products that contains freshwater (as opposed to marine) shrimp, and as such may be especially valuable.
Read also: Delicious Rainbow Recipes
Eastern Rainbowfish are omnivorous and thrive on a varied diet. Provide high-quality flakes and small pellets as their staple diet. Supplement with vegetable matter, such as blanched lettuce or peas, to meet their nutritional needs.
Recommended Foods
- Aqueon Tropical Flakes
- Color Flakes
- Spirulina Flakes
- Betta Treat
- AquaCare Tropical Tabs (containing mealworm, shrimp, and garlic)
- Live and frozen foods (especially for Pseudomugilids)
- Zoo Med’s Canned Shrimp (freshwater)
- Blanched lettuce or peas (for Eastern Rainbowfish)
Breeding
Rainbowfish Breeding Level - Intermediate Rainbowfish are egg scatterers and provide no parental care once the eggs are laid. Many Rainbowfish spawn in vegetation or can be induced to deposit their eggs in yarn mops. A slight increase in temperature will often induce spawning activity. Eggs hatch in 7 to 21 days depending on temperature and species.
Dwarf neon rainbowfish are egg scatterers, so they’re not particularly difficult to breed in the home aquarium. The fry, however, can be a little tricky to raise to maturity. It’s best to spawn your rainbowfish in a separate breeding tank at least 18 inches long. Fill your breeding tank with fine-leaved plants like java moss for your rainbowfish to scatter their eggs amongst. Once the rainbowfish are conditioned in the main tank, move the plumpest female and the most brightly colored male into the breeding tank to spawn. Dwarf neon rainbowfish often spawn several times a day over weeks. Because the adults tend to eat their eggs and fry, having plants or a spawning mop to give the young cover is essential. You may also want to monitor your fish closely and remove the adults after spawning.
Breeding Eastern Rainbowfish is relatively straightforward. Provide a separate breeding tank equipped with spawning mops or fine-leaved plants. Condition the adults with protein-rich foods such as live or frozen bloodworms. After spawning, remove the parents to prevent them from eating the eggs. The eggs hatch within a few days, and the fry can initially be fed infusoria or finely powdered egg yolk.
Raising the Fry
Three to five times a day, feed the newborns a diet of powdered fry food, vinegar eels, infusoria, and other miniscule foods. Keep the water clean with small, frequent water changes to remove the uneaten food. Eventually, graduate them to eating baby brine shrimp, which will help them to grow fast and healthy.
Health Concerns and Maintenance
Despite their inherent hardiness, rainbowfish can still get sick from dietary insufficiencies, poor water quality, and other issues that may be harder to pinpoint. While some of these conditions may sound pretty esoteric, you can usually spot the symptoms of a rainbowfish health problem. 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. 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.
Regular Maintenance
Weekly maintenance (Every Sunday) that includes 35% water change also the filter sponge wash. Then at the end of the month a filter wash of the compartment's inside the external filter.
Maintain good filtration and do a 10% water exchange every week or 25% every 2 weeks using an Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner. Don't forget to treat tap water with Aqueon Water Conditioner before refilling your aquarium!
Boesemani Rainbowfish: A Detailed Look
One of the most striking and recognizable rainbowfish is the Boesemani rainbow. This schooling fish is prized for its unique-looking, bicolored body and is the perfect statement piece for a medium-sized community aquarium. Melanotaenia boesemani has the classic rainbowfish profile with its pointed snout, deep-bodied profile, and large, distinct scales. Males grow to 4 inches (10 cm) in size and display an iridescent blue front half and orange back half. Females are less colorful, have a slimmer body, and tend to stay around 3 inches (8 cm) long. They are currently endangered in the wild, so the Boeseman's rainbowfish sold in the aquarium hobby are all captive-bred. However, the rainbowfish you see at the pet store are usually 2-inch (5 cm) juveniles that looked washed out and barely resemble their adult counterparts.
This species is found in mountain lakes and tributaries in West Papua, Indonesia and usually dwells in the shallower areas where lots of vegetation grows. Thus, they would appreciate a densely planted tank with areas of open space for swimming. In fact, one of their favorite pastimes is traversing back and forth along the entire length of the aquarium, so we recommend getting a fish tank at least 4 feet (1.2 m) in length once they are fully grown.
Water Parameters for Boesemani Rainbowfish
In general, Boesemani rainbow fish are very hardy and can tolerate a broad spectrum of water parameters. We like to keep them at tropical temperatures between 75-82°F (24-28°C). They can go warmer, but higher temperatures tend to shorten their life span. Although they are originally from mildly alkaline waters, they can easily handle pH of 6-8, and they do enjoy harder water with 8-20 dGH.
Social Behavior and Tank Mates
As a schooling fish, aim to get six or more rainbows of the same species if possible.
Because of their high activity level, we suggest keeping them with other fast swimmers of a comparable size. This includes other rainbowfish, loaches, barbs, peaceful catfish, gouramis, danios, and medium-sized livebearers.
Feeding Boesemani Rainbowfish
These omnivores are not picky eaters and will happily eat anything you drop in the tank, but they do prefer meatier foods if given the choice. For optimal health, provide a variety of dry, frozen, and live foods to ensure they get all the essential nutrients and vitamins they need.
Breeding Boesemani Rainbowfish
Boesemanis are one of the easier rainbowfish to spawn, but their tiny fry can be difficult to raise. Start by making sure you have both males and females, and condition them for breeding with heavier feedings. Set up a spawning tank with slightly alkaline pH, warmer temperature, and a sponge filter that won’t suck up the babies. Place the adults in the prepared tank with a DIY spawning mop. The male will develop a white stripe on his head and do a shimmying dance to attract a female.
Lifespan and Size
Rainbowfish typically grow between 2.5 to 4.7 inches (6 to 12 cm) in length, depending on the species. For example, Dwarf Neon Rainbowfish stay closer to the smaller end, while species like Boesemani or Lake Kutubu Rainbowfish can grow larger. With proper care, Rainbowfish can live up to 5 years or longer in a well-maintained aquarium. Their lifespan depends on several factors, including tank size, water quality, stress levels, diet, and whether they’re kept in appropriate social groups.
With proper care, Melanotaenia splendida splendida can live for up to 5 years.
The Eastern Rainbowfish (Melanotaenia splendida splendida)
The Eastern Rainbowfish (Melanotaenia splendida splendida) is a vibrant and hardy freshwater species native to the rivers and streams of northeastern Australia. Known for their shimmering colors and peaceful temperament, these rainbowfish are a popular choice for both beginner and experienced aquarists.
Natural Habitat
Melanotaenia splendida splendida is endemic to Oceania, specifically northeastern Australia. These fish inhabit a variety of freshwater environments, including rivers, streams, and lagoons, often surrounded by dense vegetation.
Tank Requirements
A tank of at least 200 liters (50 gallons) is recommended for Eastern Rainbowfish to accommodate their active swimming behavior. Maintain water temperatures between 20-30°C (68-86°F), a pH range of 5-8.5, and water hardness of 6-15°N (107.14-267.86 ppm). Provide plenty of plants around the tank's edges while leaving open swimming spaces in the center.
Identifying Male and Female
Males are typically larger than females and have deeper bodies with more intense coloration, particularly during the breeding season.