Australian Rainbow Fish (Melanotaenia fluviatilis): Ultimate Care Guide

Australian rainbow fish, Melanotaenia fluviatilis, is another fantastic choice to have included in your aquarium.  This lovely freshwater fish is both lively and colorful and a very popular choice amongst both beginner and experienced hobbyists.  The Australian rainbow fish comes in many different colors and styles, which is one of the many reasons why the fish is so popular.  The Australian rainbow fish also goes by such names as Murray River rainbow fish, crimson-spotted rainbowfish, and blue eyes rainbow fish.  The Australian rainbow fish originates from the Murray Reive Basin in the New South Wales part of Australia.  They have also been spotted in areas around Madagascar, New Guinea, and Indonesia. 

Australian rainbow fish are slightly less colorful than other species of rainbows.  They are mostly silver colored and have streaks of orange and yellow on their bodies.  The younger rainbow fish have a yellow streak down a silver body and as they mature, they develop a shiny turquoise pattern on their dorsal side, which makes them shine in the tank.  However, there are about 50-100 different varieties of rainbow fish known in the wild. 

The Australian rainbow fish is an omnivore that shines in variety of iridescent rainbow hues throughout its body.  It comes from the Melanotaeniidae family and is peaceful and good in a community of fish.  Rainbow fish are a group of around fifty different species of fish that have a lot of variety between them.  The Australian rainbow fish is easy to take care of and by following this guide, you’ll be able to create the ideal aquatic environment for your fishy friends.

Australian Rainbow Fish Care

Australian rainbow fish are very easy to take care and have an easy going temperament.  They are the kind of fish that swim openly in a tank and are not shy about it.  They are not usually aggressive with other fish, however, they have been known to nip at fins, so keep them away from fish with long, flowing fins. Other than that, Australian rainbow fish are very social and do best when they are kept in groups of around six. 

Australian Rainbow Fish (Melanotaenia fluviatilis)
Australian Rainbow Fish (Melanotaenia fluviatilis)

Temperature & Water pH

The freshwater Australian rainbow fish likes a warm water that sits between 70–80°F (23–26°C).  Anything colder than that and you open the fish to a variety of problems.  It would also be good for you to test your water quality regularly and perform weekly water changes of at least 20%.  Keep the pH levels of your tank between 6.5-8.5, but ideally at 7.0pH.  The water hardness ranges between 8-20dGH. 

Bear in mind that the Australian rainbow fish is not a very large fish, as it sits on average around four inches long.  The female is even a bit smaller at 3.5 inches.  The Australian rainbow fish have been known to get a little bigger in the wild, but not in captivity.  Their size makes it ideal to have them in a group, since they are so peaceful.

Food and Diet

The Australian rainbow fish are omnivores and will eat a lot of different foods.  Normally in the wild, they would feed on plant matter, insects, and crustaceans.  In captivity, they are accustomed to pellets, flakes, live food, and frozen food.  Since your Australian rainbow fish need a wide variety of nutrients, it is important to provide a variety of diet for your fish.  If you get baby Australian rainbow fish, then they will need more protein, for example.  You can also feed them with brine shrimp or bloodworms.  Try giving them live food about two or three times a week and keep pellets and flakes to daily foods.  Frozen food is like a special treat for them, so maybe only once a week. 

When feeding your Australian rainbow fish or any fish for that matter, you must be mindful of how much food you are giving them.  Only give them as much as they can eat in a few minutes.  Overfeeding your fish can cause some serious problems.  Plus, the Australian rainbow fish are known to be pigs and will eat as much as you give them.  They are top feeders and you might want to teach them how to feed in one particular section of the tank.  This way, they rainbow fish know where to go and what to do, which will help you better control the feeding process, especially since the Australian rainbow fish are jumpers and might try to jump out like they do in the wild.  You really only need to feed the Australian rainbow fish small portions two or three times a day and rotate their diets.  You can use gavel siphons on a daily basis to remove whatever uneaten food remains. 


The lifespan of the Australian rainbow fish is not as long as other fish.  Sadly, it only lasts about five years.  In the wild, it might lengthen a bit more, but in captivity, the Australian rainbow fish’s lifespan relies mainly on how well you take care of the aquarium.  Giving fish their exact ideal conditions is the best way to extend their life and have your fish thrive.  Any kind of neglect or lack of cleanliness will have an effect on the rainbow fish and could cause disease, bacteria, or even death. 

Tank Size & Tank Setup

When figuring out what kind of aquarium you want, you really have to think about the tank size and how many fish you wish to include inside.  Australian rainbow fish can handle a twenty-gallon tank, but if you plan to group up your Australian rainbow fish, then you might want to give them a bit more swimming room and get a thirty-gallon tank.  Depending on what kind of tank mates you have with the Australian rainbow fish will also have an effect on what tank size you should go with. Think about adding two gallons for every extra fish you get. Important note, Australian rainbow fish are jumpers, so make sure your tank has a lid. 

As for the setup, remember that the Australian rainbow fish are not shy swimmers and if you give them the space, then they will nestle themselves into many different areas.  Australian rainbow fish prefer a substrate as dark and sandy, as this brings out the best colorization.  Plus, they like to dig.  Most rainbow fish are accustomed to brackish water and goes well with bogwood or roots. 

The tank itself should have as many hiding spots as you can create throughout the tank.  You can do this with vegetation, rocks, and caves.  Just make sure to leave a lot of space for swimming.  Again, this is another reason why it is best to plan out your aquarium before you get the fish.  The more fish, the bigger the tank, the more hiding spaces to create.  Have a filter attached to the tank and keep an eye on the water levels. 

Some of the better aquarium plants recommended are java fern, amazon sword, anubias, water wisteria, if you’re browsing different plants.  Australian rainbow fish like to nibble on the plants. 


If you are so bold to take on the task of breeding the Australian rainbow fish, they are quite easy to breed in an aquarium setting.  They are egg-layers and will likely lay their eggs on any plants or rocks towards the bottom of the tank.  The female will lay around 1000 eggs at a time and then the male fertilizes the eggs.  It’s all very romantic and the thee eggs will hatch within four to seven days.  The fry will be swimming on their own a few days after that.  This is where that aforementioned protein comes in handy.  The fry can be fed newborn fry shrimp and microworms.  The fry will grow fairly quickly with that diet and within a few weeks, they should be able to digest pellets and flakes like normal.  Remember to plan well for this event, as you will probably need more than one tank to hold a growing number of fish.  You should prepare with at least a twenty gallon breeding tank so you’re ready to go. You might also want to have a water warmer, which would keep the water temperature at 86°, which will help in the breeding process. 

To tell the difference between the males and females, you can look at the size, for one.  Females tend to be a little smaller than the males.  However, another way to tell the difference is to look at the anal fin.  Male rainbow fish have longer and narrower anal fins than the female.  Also, male rainbow fish usually are a bit more brightly colored than the female.  It’s best to wait until they are fully grown adults to really be able to tell them apart. 


Yet another reason that makes these Australian rainbow fish so amazing is that they are relatively disease resistant and can tolerate different water conditions because of their hardiness.  That being said, you still need to take care of the tank and water while keeping an eye out for white spot diseases or ich.  Australian rainbow fish can also get fin rot, which is a bacterial infection that affects the fins and tail of the fish.  The fins become frayed and will eventually disintegrate, which would be fatal if not treated timely.  Velvet is another parasitic infection that will cause the fish’s skin to turn yellow or brown.  Velvet will also cause the gills to become inflamed.  The best way to avoid any of these diseases is maintain a stable, clean environment for your Australian rainbow fish.  Remember not to overfeed them, change the water, and be sure to quarantine new fish before adding them to your main tank. 

Tank Mates

As mentioned before, Australian rainbow fish are generally peaceful, non-aggressive types that get along with a number of different tank mates.  It is important to note that your tank size will need to increase based on how many fish you decide to have.  Since Australian rainbow fish are already grouped fish, think about what other tank mates would be a good match for them. 

For example, Australian rainbow fish get along with Boesemani and Madagascar rainbow fish.  They also like black phantom and black skirt tetras, zebra danio, chili and emerald dwarf rasbora, and honey and opaline gourami.  It is best to avoid smaller fish, as there is a possibility of them getting bullied by the bigger fish.  You can also group them with less males to help reduce aggression within the tank. 

Since the Australian rainbow fish is such a quick swimmer, it might be best to avoid any kind of fish that are slow swimmers.  A tank that small will feel very crowded if traffic is held up by some slow fish.  Other fish to avoid with Australian rainbow fish include any overly aggressive fish species like cichlids and bettas.  They tend to bully the rainbow fish. 

Where to Find an Australian Rainbow Fish for Sale

If you are looking to buy some Australian rainbow fish, think about the age of the fish.  If the rainbow fish is a juvenile, then it may cost somewhere between $12 and $18, while a fully grown adult may cost between twenty and thirty dollars.  However, they have been known to cost up to $50.  The best way to buy Australian rainbow fish is to buy them in bulk, because you might get a discount.  Since rainbow fish are fairly popular, they aren’t generally too expensive. 

You can pick up the Australian rainbow fish at many Petsmart or Petco.  However, if you are looking to buy a fish, your best bet is to make your way to a reputable local fish shop.  It is more likely that these fish will be better taken care of and grown.  The workers also tend to pay more attention to the water levels and are able to answer more detailed questions.  So please pay mind to where you get your fish from and make sure your tank is setup before you purchase.