Updated August 3, 2019
Author: Mike - FishLore Admin
The Rainbow Shark is a freshwater cyprinid that comes from Thailand and may not be a good choice for a community tank. This fish likes to stake out their own territory in the tank. This territory can be in the form of small caves, rocks and even live plants. They will become aggressive with smaller fish that invade this territory. Only keep one of them in your tank because they will not tolerate another Rainbow or Red Tail Sharks in the same tank. They may exist together for awhile, but one will end up chasing the other relentlessly until the other succumbs. You may also see an albino variety that is sometimes available at your local fish store.
Breeding this freshwater shark is rare in the home aquarium. This is most likely because of their intolerance of each other in the small confines of the home aquarium.
You will need a good tight fitting hood with no escape points because thy have been known to jump out of the tank.
Rainbow Shark Care Details
Scientific Name : Epalzeorhynchos frenatum
Common Names : Red Fin Shark, Red Shark, Ruby Shark, Albino
Care Level : Easy
Size : 6 inches (15 cm)
pH : 6.5 - 7.5
Temperature : 75°F - 80°F (24°C - 27°C)
Lifespan : 5 - 8 years.
Origin / Habitat : Thailand, Indonesia
Temperament / Behavior : This fish can become aggressive with other, smaller fish in your tank that invade its territory. They will fight with the Red Tail Shark. Provide plenty of hiding places (caves, rocks and plants)
Breeding : Because they will fight with other rainbows, breeding them in the home aquarium is rare. Higher hatch survival rates occur in softer water vs. harder water.
Aquarium Size : 55 gallon (208 liters)
Tank mates : Because of their temperament it is a good idea to house them with similar sized fish. Do not keep with other Rainbow sharks and Red Tail Sharks
Fish Disease : Freshwater Fish Disease
Diet / Foods : An herbivore - provide a varied diet with algae wafers, pellet food and frozen food.
Tank Region : Mostly bottom to middle
Gender : On males, the anal fin is outlined in black
Photo Credit : Photos copyright JJPhoto.dk
Rainbow Shark Comments and Tips
Based on my prior experiences I suggest you do not feed them algae wafers because they usually do not eat them. Secondly, make sure the tank's pH is stable. Sometimes it may cause the shark to become hyper and become more hostile. In some other cases the wrong pH might make them seem lethargic and not eat.
I have had my rainbow for about 6-7 months now. He was in a tank with some danios, a few other fish and 2 dwarf frogs. He was fine until about a week ago when he started getting really aggressive with the other fish and actually attacked one of the frogs to death. I took him out of the tank and put him in a separate bowl for the night and was going to take him back to the store for a trade-in. Well, he did not survive the night as he jumped out of the bowl and I found him dead and crusted on the kitchen floor. Watch out! These fish can become vicious out of no where!
I have had my shark for about 14 months now. When I first got him he was pretty young and only a couple inches long. He was pretty calm for a while, but as he got older he began to become territorial. I had to buy a hollow log decoration for him to hide under because he became a wuss too! He nipped the fins of my black skirt tetras, long-finned serpae tetras, and cories. I ended up just getting danios to live with him because they are very quick and can out swim him. I really like him even though he is territorial, and he has always been healthy. He is up to about five inches long now, and I just put him in a bigger tank, so I hope he gets a little bigger. It is very entertaining to watch him because of his distinct personality!
I have 4 Rainbows, 4 Silver Sharks and a Bala Shark for almost 3 years now. This little community seems to work perfectly. My sharks are playful, they hide, but love to come out and play. I named the one Pebbles, as he loves the marbles in my tank (pushing them around all over). My tank is well planted and with many hiding places. I think the Rainbows might just be a little misunderstood. Mine are generally calm and peacefull. I have however found that they do not like fish smaller than what they are. Hope this can help. I am not an expert on fish, but I love them. Currently I have 4 tanks, all different species divided into communities.
I have had an albino rainbow shark for years now. He's gotten long and real thick! He's at least 7 inches long, and almost an inch wide! Its hard to believe! When I first got him he was almost eaten by my oscar (had him in mouth) but I saved him and now he owns his current setup with 17 tiger barbs, 1 bala shark, 1 parrot fish, one pink convict cichlid, 1 florida flag fish, one paradise fish, and some algae eaters. They all get along great and there is never any fighting. I think mine might be a record in size!
6 months ago I got one of these sharks for my new tank. It just keeps getting bigger and bigger! I put him in a bigger tank where he stressed out and got ick. I put him back in his original tank and all he does is hide in the plants all day. He is very shy and shares his tank with one tiny, also shy plecostomus.
My experience with rainbow sharks is in line with what I've read here. My first tank included 2 rainbows, with an assortment of other good community fish. When I set it up I knew basically nothing and relied on the advice of the salesman. The sharks were so pretty I wanted 2 of them. Both were females. One was a good bit larger than the other. Sure enough, within a few days the larger started harassing the smaller - just constantly seeking her out and chasing her. Not really biting or tearing, just chasing. The big one pretty much ignored the other fish in the tank. It has continued for a few months and although the smaller has survived and still looks healthy, she just constantly hides behind plants, heaters or situates herself vertically in various corners of the tank. I feel so sorry for her. She doesn't seem to be enjoying life. The other one is so cocky and just swims around like she owns the tank.
I sure wish the salesman had told me the advice I have read here that you shouldn't get 2 of these together. To this point, the big one hasn't really bothered the other fish (including some small guppies) but that may come as she gets larger. I check the tank every morning dreading seeing the smaller one having just given up the ghost out of fatigue or stress. Should I get rid of one? I can't stand to just kill one. What is the procedure for returning a fish? Just take it back? I'd assume they would just dispose of it since it's not an expensive fish. The bad part is that I like both of them - the small one is beautiful and the big one has a great presence (aside from her bullying). Any advice?
Yep, take one of them back to the store and let them know of your experience and about what you have read about this fish's behavior. Maybe the sales clerk didn't know you shouldn't keep multiples in the same tank. If you told them, maybe it would prevent them from selling the next guy two of these rainbows. Definitely take it back and ask for a refund, or at least a store credit. They won't dispose of it. They will try to resell it. Do the right thing here.
Don't get two of these! I just bought 2 tonight from pet store, ticket showed they were passive, and I asked the sales woman if they were aggressive and she assured me they weren't. Got them home and put them in the tank and one has been harassing the other one all night. I'm taking the aggressive one back tomorrow, but keeping the other because it is very passive so far with other smaller fish and doesn't seem to mind them.
I wouldn't recommend them for a community aquarium. I never bought two, but I had one about a year and a half ago and whenever any fish smaller than him got near the middle, or bottom of my 20g tank he'd chase them as soon as he saw them. I brought this fish back, and the salesperson understood; most stores will take these back if you just explain why you bought them.
Though all fish have different personalities, the rainbow shark seems to be an all around aggressive species if kept with other fish. They are attractive fish, so if you must buy one, make sure you have a tank large enough for the other fish to swim around freely without aggravating it.
Excellent comment - thank you.
I must have the pick of the litter when it comes to my rainbow sharks. I've seen a number of forums about these guys and many complain about them being aggressive, I just don't have that problem. So I must have the 2 biggest sissy rainbows. One I've had for 10 months and is about full size, while the other is new to the community about 4 to 5 months and half the size of the other one. I have them in a 20 gallon tank and they could care less about each other. The bigger one has his home in a log, while the other one swims around hanging out with the sword tails. When they come into contact with one another, there is no chasing or aggressive posturing. I'm no fish expert so I can't say why these 2 would get along, I just seem to have gotten lucky.
Thanks for your comments. You're right, this doesn't seem to be the norm when keeping multiples.
we have had our tank for about a year now, it consists of platys, zebra danos, corys and now our one rainbow shark. When first setting up our tank we bought one rainbow and one albino. At first they were fine with each other but as they got bigger the albino became very dominate with the other fish and would harass the other shark. The rainbow wouldn't eat and stayed very small. I found a home for the albino and now my rainbow shark is growing, seems happier and is a bit more active with the other fish.
Hi, there is a very simple rule for rainbow n red fin sharks, and some other semi aggressive fish like blue Gourami, either keep single in an aquarium or keep atleast 4-5, that way the dominant one doesnt always chase the same fish of its species and all get enough time for rest beside company, i have 5 red fin and 1 rainbow, often they do their dominance dance around each other, if u know what i mean, but meanwhile a 3rd or 4th fish comes by and their focus shifts, day saved!! Its interesting to watch their moves and all, but ive never had any issues keeping 6of the same species, if its just a pair naturally the dominant one will always chase the same fish again n again all day long, killing its personality, the golden rule is, either keep 1 or many, 4-5 at least, never a pair!
My Rainbow Shark always jumps out of the tank. Once he was almost rock hard after being out of the water all night and I put him back in and he survived.
I have had my rainbow shark for almost 2 months, and it is getting more aggresive. It does not like my tetras that I put in the tank, and it keeps trying to attack them.
Why do these fish have to be kept in such a large tank if they only grow to be six inches long? I have 29 gallon tank with a sailfin pleco and 3 bleeding heart tetras would this fish get along with them?
Rainbow sharks are very active swimmers that need more open space for swimming and to limit any territorial aggression that may crop up. Theoretically, this mix of fish should be ok... The pleco will handle itself well and the rainbow should leave the tetras alone. Also, the sailfin pleco is going to get too big for a 29 gallon tank. Time to get a bigger tank. More tanks - woo hoo! :)
Hi. I'm a newbie and recently started a new aquarium. I started with a rainbow shark and a betta fish. They started off fine together but now the rainbow shark is showing signs of aggression by chasing and nipping the betta's fins. Help?
Obviously, you need to separate these two fish by using a tank divider or return one of them to the store. Rainbow sharks can get aggressive with their tank mates, especially in smaller aquariums with cramped conditions.
I have two redtail sharks and one rainbow shark, with three tiger barbs, three black phantom tetras, and three bleeding heart tetras, a small plecostomus and a molly. The different sets of tetras and barbs school together (three schools) and the sharks don't bother them. The molly is big enough that they don't mess with him, and the plecostomus is always on the floor and isn't much bothered either.
One way to keep them from jumping out that I have found helpful (after having one rainbow jump out) is to float a bunch of plants (fake or real) on the top of the water. It seems to serve as a ceiling that keeps the sharks lower. Hope this helps.
I haven't had a fish tank for long, as we got it when we recently moved home. We were told by the store all the fish we had together were ok together, we got guppies and a rainbow shark. Recently one of the guppies was found dead in the tank and I'm noticing that every day a few of the guppies tails look like they been nipped at. Do you think it could be the rainbow shark doing this? I also wanted to know if the light need to be kept on at all times?
Depending on the tank size (cramped confines can lead to more aggression), it could be the rainbow shark doing the nipping or even the neons or other guppies. Watch them closely and take corrective action if needed. You may want to invest in a tank divider or remove the rainbow shark (if he's the culprit).
You definitely want to have some down time with the lights off for your fish. Please read the aquarium lighting article for more information.
I've had my rainbow shark for over a year now, originally in a very small tank with platies, tetras and gouramis. That didn't go so well so we moved him into a tank of his own until we could afford a bigger tank. We've now got that and had him in it for nearly a year with zebra loaches, cory cats, and a whole bunch of different tetras. He is territorial and will chase others out of his hiding holes and away from what he deems as his food but that is as far as his aggression goes. He really is a delight to own.
I've had my Rainbow shark for 3 years. I had him by himself for the longest time, but now have him with Tiger Barbs and Rosy Barbs. He does get cranky with them, but they out swim him and they leave each other alone for the most part.
I have an amazing Rainbow Shark. He lives in my 30 gallon community tank, in a hollow log. He makes a game of chasing the other fish, especially light colored ones! He was really small when i got him (less than 3 inches. He is absolutely HUGE now - 7-8 inches! And amazingly last month marked 8 years that I've had him! I never see anyone who has one this old! About 4 weeks ago I had a big scare. While cleaning his tank, I walked across the room and he LEAPED out of the tank and fell to the floor. He tore off the entire upper part of this tail fin and had several scales damaged. When I put him back in he was floating on his side. I treated him with Melafix and Nitrofurazone - changing water every other day - and 4 weeks later he is swimming around, chasing the fish as always and his tail is starting to grow back! He's a tough old guy! What a great fish.
We have had our rainbow shark for about 2 years now. He is fairly aggressive with our other fish so we finally bought a divider for the tank. We put the shark and the barbs on one side and we keep the milder fish on the other side. So far this process is working out very well. Occasionally some of the smaller fish get over to the "aggressive" side of the tank and we just rescue them and put them back over on the "passive" side of the tank.
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