Rainbow sharks are renowned for their unique appearance and close resemblance with large ocean sharks.
Though popular, they can be difficult to keep. This guide will run through everything you need to know about rainbow sharks, including housing, ideal water parameters, feeding, and breeding techniques.
Let’s get started.
What are Rainbow Sharks and Where do They Come From?
Part of the Cyprinidae family, Rainbow Sharks are relatively small, attractive looking freshwater fish.
Natively, these sharks live in the river basins of Mekong, Chao Phraya, Xe Bangai and Maeklong, all of which are bodies of water in the Indochina region.
These fish have a distinctive appearance: long, dark bodies, pointed snouts and a flat abdomen. Their fins are typically red/orange in color. When fully grown, rainbow sharks can reach 6 inches in length.
They’re highly-territorial fish and are prone to aggressive behaviors towards other, smaller fish.
Are There Different Types of Rainbow Shark?
Generic breeds of rainbow shark usually have dark blue/black abdomens with red/orange fins.
Male rainbow sharks usually appear slightly lighter in color than females, though their appearance is still quite similar.
Since breeding rainbow sharks is really difficult, there aren’t many different varieties; the only alternative type known are albino variants.
These sharks have bright white abdomens with red fins and eyes. Albino breeds are extremely rare.
Part 1: Preparing and Setting Up Your Rainbow Shark Tank
When housing a rainbow shark, there are a number of specifications you’ll want to take into account.
Let’s go through them together, one-by-one:
The Best Aquarium size for Rainbow Sharks
Even though rainbow sharks aren’t particularly large, they are semi-aggressive and highly territorial.
For that reason, you should have a minimum aquarium size of 50 gallons (long) for a single fish and around 125 gallons per 2-3 fish (again, you want a long aquarium).
Sounds like a lot, right? Well, it’s for good reason:
Basically, rainbow sharks need all that extra space to be comfortable (even better if your aquarium has a few hiding spots they can use to avoid conflict with other animals).
What Type of Substrates Work Best for Rainbow Sharks?
Rainbow sharks prefer sand substrates, as their native waters are lined with sandy bases.
Many aquatic hobbyists favor sand, simply because it’s easy to clean and rarely collects food or waste.
You can use gravel, too, so long at it’s quite fine (larger, sharper chunks of gravel can cause damage to your fish, scratching at their skin and leading to infection).
On top of that, gravel also has a tendency to gather waste. Although, saying this, there are countless hobbyists who have beautiful and successful aquariums using gravel.
If you choose to use gravel, make sure you clean it regularly in order to maintain adequate water hygiene.
How Much Filtration is Needed for my Rainbow Shark Tank?
Rainbow sharks are used to fast-flowing waters. Not only will your rainbow shark be most comfortable in this kind of environment, but you’ll also find there are a few other benefits of keeping a fast-flowing aquarium:
Implementing a strong filtration system will:
a) increase water flow (which means a happy rainbow shark) and b) help maintain water quality by filtering out any organic waste (even happier rainbow shark).
Using both an internal and an external filter in your aquarium is an excellent way to increase water movement.
Other ways you can increase water flow is by using air pumps and stones, water pumps, and aquascaping (more on this later).
And when it comes to choosing your filter(s), you’ll need to understand GHP. It’s super important.
Here’s the deal:
Filters are measured in gallons per hour (GPH). Water pumps and filtration systems will be tagged with a GPH rating, which is what determines how many gallons of water will be taken in and filtered each hour.
You should always aim for a minimum GPH 4 times the size of your tank. So a filter for 100 gallon tank should have a minimum GPH of 400.
Pro Tip: GPH rating is often based on low stocked aquariums or empty ones, therefore it’s always best to go a bit higher if you’re looking to make your life easier when it comes to maintaining your aquarium.
What Kind of Lighting Should I get for my Rainbow Sharks?
Rainbow sharks don’t need any specialist lighting.
However, I always recommend LED aquarium lights because they’re cheaper to run long-term and are often programmable so you can easily provide natural day/night cycles.
Really, your lights will depend on the types of live plants you want to keep. But again, when it comes to freshwater aquarium plants a natural day/night cycle with LED lights will be fine.
Should I add Plants and Decorations?
Yes, of course!
I advise you add plants and decorations to your rainbow shark aquarium to allow it to hide and minimize potential confrontation with other fish.
Even if you keep your fish alone in the aquarium, you might want to consider putting in some hiding spaces like caves, driftwood, and other decorations to make them feel more at home.
You can use both live and fake plants, so long as the fake ones don’t have sharp edges that could harm your fish.
Personally, I always pick live plants over fake ones because they don’t take much work, look great, and will help keep your water clean.
Part 2: Creating Your Habitat: Ideal Water Parameters for Rainbow Sharks
When housing a rainbow shark, you should aim to replicate the conditions of their natural habitat as best as possible. This section will walk you through how to do that.
Important: The first step you should always take when starting a new aquarium is to ensure you have fully cycled your tank. You can see a simple step-by-step guide here about the Nitrogen Cycle.
The temperature of your shark’s water should be between 72 to 82℉ – though you should try to aim for a stable temperature of around 77℉
Pro Tip: If you struggle, don’t worry. The key is to not chase the perfect temperature, but to keep it stable between these values. If your fish aren’t showing signs of stress–don’t stress 😀
You see, even though experts agree that temperatures within this range are safe, it’s important that the temperature of your water remains more or less fixed.
If, for instance, your water is constantly bouncing up and down between 72 and 82℉, you increase the chance of your fish becoming stressed, making it susceptible to disease.
One of the best ways to avoid this, is to invest in a high-quality heater that effectively maintains an appropriate temperature.
As we mentioned already, rainbow sharks are used to being in high-flow waters, like those of the Indochina river basins.
To achieve this, you may need to add more than just an external filter to your tank. You should also consider adding a horizontal filtration system in order to keep your water flow high.
There are a number of other ways to increase water flow, too, including:
- Adding air stones and placing them around your tank
- Aquascaping (keeping your tank more open by removing objects like plants and decorations that would otherwise soften water flow)
- Powerheads – small jets that propel water to increase flow
- Wavemakers can be used to produce oscillating waves, similar to those of reef zones
- Closed loop systems can can create water flow throughout a tank without necessitating powerheads (however, these often require you to drill into your tank. If you already have it set up, closed loop systems probably aren’t your best option).
If you find that your water flow is too high (identifiable by your fish being unable to swim comfortably), you can add in dense decorations like driftwood to soften it.
What pH Should I Have?
Rainbow sharks prefer pH neutral waters between 6.5 and 7.5. Again, like the temperature, aim for a stable number between this range.
Understanding Chlorine and Chloramines
Listen up, because this section is extremely important for the wellbeing of your rainbow fish:
Tap water and most municipal water supplies contain traces of harmful chemicals like chlorine, mercury, and lead, which are used to eliminate harmful microorganisms from drinking supplies.
Such chemicals are not only harmful to microbes, but mammals, humans and, most importantly, your fish.
Chlorine, in particular, can become incredibly toxic when it reacts with ammonia – a product that we can find in the excrement of most fish- meaning you probably have it in your fish tank.
This reaction between chlorine and ammonia produces compounds known as chloramines, which are also seriously harmful- and can even be life-threatening.
The combination of chlorine, chloramines, and ammonia in your fish’s water combine to create a highly-toxic chemical cocktail, leading to illness and, most often, death.
Pretty scary, right?
Thankfully, these chemical levels are fairly easy to control.
Here’s the number one golden rule:
You should never add tap water directly to your fish’s aquarium. Instead, run that water through a dechlorinator – a chemical additive that effectively eliminates chlorine and chloramines.
Once that’s done, you can purchase chlorine test kits from most merchandisers to check that your water levels are safe before use.
Understanding Ammonia, Nitrite, and Nitrate
Ammonia is a waste product of fish. When unionized, it can become incredibly toxic.
Ammonia unionization can happen in a number of ways – one of the most common being through high water pH. High pH levels force ammonia to remain in its unionized form.
Above a pH of 8.5, ammonia toxicity can bring serious harm- and even death- to rainbow sharks.
As if that didn’t pose enough of a risk already, ammonia can break down even further to form another toxic compound called nitrite.
And although nitrite isn’t as harmful as ammonia, when nitrite breaks down to form nitrate, it can build up easily and cause problems for your pets.
You might be wondering what kind of problems we’re talking about, right?
Build-ups of nitrite/nitrate can encourage algae blooms, which affects water pH by blocking light from entering your tank.
The good news is that you can easily manage ammonia, nitrate, and nitrate levels by:
- Performing the Nitrogen Cycle before you add your fish.
- Performing regular water changes and dechlorination.
That being said, it’s still wise to conduct regular water testing to ensure that your chemical levels are kept at a safe level.
You can purchase ammonia, nitrite, and nitrate test kits from most aquatic merchandisers.
Part 3: Rainbow Sharks Temperament and Suitable Tank Mates
As we’ve already touched on – rainbow sharks are highly territorial fish with aggressive tendencies.
Many aquatic hobbyists advise against introducing tankmates to a rainbow shark, but it is possible.
But, if you’re a complete beginner I would advise against it.
If you decide to house your fish with others, you must ensure that those fish are also semi-aggressive and of a similar size.
Some examples of suitable fish include fish from the Chromobita, Botia, Syncrossus, and Yasuhikotakia genera. Gouramis, barbs, and danios also make good companions.
If you fail to add equally-aggressive fish to the same aquarium, the larger fish in the tank are likely to seriously harm, if not kill, the weaker fish. Small fish and bottom-feeders are the most common species for rainbow sharks to pick on.
Furthermore, it’s important that you house more than just one other fish with your rainbow shark.
As your fish are likely to squabble from time-to-time, having several will ensure that one pair of fish aren’t endlessly fighting and injuring one another.
Part 4: Dietary Requirements and Feeding Your Rainbow Sharks
Rainbow sharks are naturally omnivorous fish. They require a diverse range of foods in order to remain healthy.
What Can I Feed My Rainbow Shark?
Rainbow sharks will feed on most common fish foods, including pellets, flakes and algae wafers. As they are primarily bottom feeders, you should ensure that these foods sink to the base of your tank.
Your shark will also enjoy feeding on a few small crustaceans and insects per week, such as brine shrimp, bloodworms, daphnias, and artemias.
Lastly, you should aim to implement some vegetables into your shark’s diet, too. Sliced or boiled zucchini, boiled peas, romaine lettuce – all of these work well and provide a high nutrient content.
Be sure to let them cool before adding them to your aquarium and keep an eye on them so you can clear it out any organic waste before it begins to rot.
How Often Should I Feed My Rainbow Shark?
Overfeeding fish can be a real problem, so as a universal rule I recommend feeding your shark once a day and seeing how your little buddy reacts.
If you find your rainbow shark isn’t eating all of the food in one go, feeding it a half portion in the morning and the second half in the evening is a good way to go.
This way, you’ll avoid having leftover food in your aquarium.
Part 5: Rainbow Sharks Biology and Breeding
Before attempting to breed a rainbow shark, there are a number of factors to consider:
How to Sex Rainbow Sharks
Sexually mature female rainbow sharks will have considerably thicker bodies than males and tend to be darker in color.
Meanwhile, sexually mature males often have black lines on their anal fin.
The Breeding Process for Rainbow Sharks (It’s Very Difficult)
Firstly, you should acknowledge the fact that the chances of breeding your fish to produce offspring are very slim.
Next-to-no cases of aquarium-based breeding have been documented to date. Most hobbyist believe this is due to their intolerance of each other in an aquarium.
When attempting to breed a male and a female, there are a number of measures you can take to improve your chances of success.
Setting up Your Breeding Tank
If you are willing to take the challenge, this is what you need to know:
- You’re going to need at least 75 gallons of aquarium space (the bigger the better).
- Plants and other aquairum decorations.
- You should add liquid dechlorinator to your tank to neutralize any harmful chemicals and place rocks and decor around, offering shelter if one wishes to hide from the other.
- You must install your aquarium heater to maintain a consistent temperature between 72 – 82℉. Add your filter and allow 48 hours to create a clean, suitable, and breeding-friendly environment.
- It’s also wise to have your sharks sexed by a professional before selecting a pair, as this is difficult to do as a beginner.
Once your breeding tank is fully prepared, add your pair and wait one week to ensure that the couple tolerate one another. If they fight, you may need to introduce a different pair.
To encourage breeding, feed your sharks plenty of protein-rich foods, like brine shrimp and bloodworms, and change 25% of their water once weekly using a bucket.
The sharks may then begin to exhibit mating behavior, which you’ll be able to identify if you see them rubbing against one another.
After mating, the female will scatter her eggs across gravel before your male fertilizes them with milt spray.
Caring for Rainbow Shark Fry
If you are able to successfully breed your rainbow sharks, you’ll then need to setup a tank for newborn fry.
This tank should contain 10 gallons of dechlorinated water as well as a heater and live plants.
Transfer any eggs into this tank using a nylon net. Newborns should hatch after several days, feeding off their yolk sacs following birth.
Once these sacs are depleted and no longer being used, feed your fry liquid food for 1-2 weeks before introducing baby brine shrimp.
Move newborns into your main tank only once they reach 0.5 – 1 inches long.
Important: You don’t add a filter to the fry tank because they may be sucked up inside. Adding live plants will help filter the water and perform 25% water changes every couple of days.
More Rainbow Shark FAQ’s
Here are some more frequently asked question about Rainbow sharks.
How big can Male and Female Rainbow Sharks Grow?
Rainbow sharks of either gender can reach up to 6 inches in length.
At What Age do Rainbow Sharks Mature?
From my research, there doesn’t seem to be a specific age, rather, it’s a size thing. Rainbow sharks tend reach sexual maturity once they grow to around 4 inches in length.
How many Rainbow Sharks can I keep in a 50-gallon Tank?
Due to their aggressive nature, I recommend only one.
If your questions have not been answered in this guide, please comment below and I will do my best to answer you.
Thanks for such a great article. I was wondering if I should have more than 1 Rainbow Shark in my community tank and you answered that question. My current Shark seems happy, he has his hiding spot and only chases the Neons around a little bit. Sadly, my last one jumped out of the tank and died before I found him. I’ve put a screen over the top and anchored the corners so that doesn’t happen again.