Oscar tank mates. Along with each species names are notes regarding keeping that species as Oscar tank mates. The intent is not to create a species profile, but simply to give you a heads-up regarding special issues regarding keeping that species with Oscars. As you should with any new fish, please research the species before you add it to your Oscar tank. Simply pasting the species name into Google will normally give you a wealth of information. Note that I have not personally kept many of these species, so just be warned that it is possible that there may be some issues with these species that I am not aware of. I asked for tips from those with more than 6 months of experience with the species, so hopefully, they are fairly reliable recommendations. I note the member who provided the information at the end of the discussion of each species.
If you have any species to add, or additional comments on a species already covered, and have at least 6 months of experience keeping it with oscars, please respond here with the species name, and any special considerations for keeping it with oscars.
The most important aspect of mixing any aggressive cichlid in an aquarium is the tank size. It has been said that if you have an aquarium large enough, you can mix any fish. The question is how large does your aquarium have to be to combine them. The minimum size tank that is universally recommended for one full grown oscar is 55 gallons (4ft). In that size tank, no other tankmates can be recommended. There is not enough territory for two fish to establish separate claims, and therefore the aggression would be excessive. In a 75 gallon tank (4ft) a few tankmates are acceptable. One to two small cichlids (between 3-5 inches) or one medium cichlid (between 6-8 inches) is acceptable. The determining factor, of course, is will the oscar accept them. Highly aggressive males are not good candidates for tankmates, even in a 75g. When you mix cichlids there will always be some level of aggression. Deciding when the aggression is out of hand is up to you. In a 125 gallon tank (6ft) your options grow drastically. The recommended stock list from site to site and person to person will also vary much more. I am of the opinion that a 6 foot tank can house 3 large cichlids (~12 inches), 5-6 medium cichlids, and between 10-15 small cichlids; all of this barring any excessive aggression or breeding.
Convicts (Cichlasoma nigrofasciatum) ***** 75 Gallons: Never keep a male-female pair of convicts as Oscar tank mates. Breeding convicts are simply too agressive for Oscars. However, one or more same-sex convicts will do well with oscars. The desired water parameter range for convicts is on the harder side than what oscars prefer, but if your water is somewhat hard already, and your oscars are acclimated to it, the convicts should do just fine. The convict really is the perfect Oscar Tank Mate. They are small as compared to the large bulky oscar and will not contribute significantly to the bioload of the aquarium. The majority of convicts are also very bold, and resilient. Not only are they aggressive enough to live with a much larger tankmate, but they are tough enough to brush off the occasional chase.
Thorichthys meeki (Firemouth) **** 75: Firemouths are similar in size to convicts so they compliment the giants size. They are not quite as bold or as aggressive as convicts. For that reason some will shy away from confrontation and hide. Still the two are compatible.
Jack Dempsey(Cichlasoma octofasciatum)*** 100 Gallons
Dempseys can be good tankmates for oscars. They are a medium sized cichlid. Some can be extremely aggressive, and some can be very timid. Some males have also been known to reach 12 inches in length (though 8-10 is more common). This one is hit or miss.
Temperament: An very aggressive cichlid found in South Mexico, Guatemala and Honduras. They can grow up to 8-9 inches on the average. This is a great fish if kept as “single” addition (male or female) to a larger tank. They are very territorial when spawning so I don’t recommend adding a pair unless you have at least a 6 ft long tank. Even then, your Oscar may get bullied into the far corner. Water Quality: pH 6.5-7.5, Temp 72-77 deg fahrenheit (although they do well at temperatures closer to 80 deg fahrenheit). Food: They are omnivorous so watch your plants. Mine are also partial to crickets, worms, shrimp, krill, pellets, flakes, zucchinis and peas. – dvross
Severum: Severums are generally peaceful, at least by cichlid standards. They also get nearly as large as an Oscar. In general, Severums can be considered one of the preferred tank mates for Oscars provided the tank is large enough.
Aequidens ‘goldsaum’/’silversaum’ (Green Terror) *** 75 Gallons
Description as per Rocio octofasciatum. One aspect of the Green terror that is often overlooked is their slow growth rate. Green terrors often will grow to 5-6 inches at 1/2 – 3/4 inch per month, but after that their growth really curbs. In general, Green Terrors may be too aggressive for the usually more passive Oscar. In a 6ft tank, the two species have a decent shot at getting along peacefully.
Parachromis managuensis (Jaguar cichlid) *** 125 Gallons
Jaguar cichlids have a bad reputation for being overly aggressive. Many of them are very aggressive, but some are fairly laid back. In a 6ft tank, the two species have a decent shot at getting along peacefully.
Cichlasoma salvini (Salvini’s cichlid) *** 75 Gallons
Salvinis have been described as a ‘reclusive’ fish when they are not breeding or defending their territory. They can be excessively aggressive, but their cautious nature keeps them hidden most of the time.
Heros efasciatus (Severum) ***** 75
Severums are relatively docile fish. They will mostly keep to themselves, but won’t be pushed around. Although they can reach 10-12 inches, they have a very thin profile and shouldn’t overwhelm the bioload. Severums are an excellent choice as an Oscar tank mate but, with any cichlid, there are no givens.
Hypselecara temporalis (Chocolate cichlid) **** 90
Description as per Heros efasciatus. I recommend a 90g aquarium for Chocolate cichlids because they are a bit more bulky and messy. Their bioload is more significant therefore a 90g is more suitable.
Herichthys carpintis/cyanoguttatus (Green texas/Texas cichlid) **** 125
Texas cichlids are a bit more aggressive than your typical cichlid, and most likely will not submit to an oscar. Their size and aggression make them unsuitable tankmates for most cichlids in anything smaller than a 6ft tank. Therefore I recommend a 125g tank for the two to live peacefully.
Amphilophus labiatus/citrinellum (Red Devil/Midas) ** 125
Red devil/Midas are big, bulky, aggressive fish. Even in a 6ft tank, its hard to predict success with an oscar. Though it can work, mixing these two fish is a risk.
Multiple oscars *** 125 Gallons (6ft tank)
The bare minimum tank size I would recommend for two oscars is 125 gallons. Mixing oscars is really just like rolling dice, it’s a gamble. Sometimes you’ll have two that get along great and sometimes you’ll have two that cannot live together peacefully even in a 6ft tank. The pairing process can be misleading as well. Most juvenile oscars are quite social and will often swim side by side with tankmates as if they were inseparable. However, when oscars mature they often become more fond of solitude and can become aggressive toward a former mate.
Keeping more than two oscars can be tricky. The number three is seemingly an unlucky number when it comes to these particular fish. The situation almost always plays out as two oscars teaming up and bullying the third oscar relentlessly. Naturally, one would think that the two fish that pair up are male and female, but this is not always the case. Sometimes two females team up and bully a male; sometimes two males team up and bully a female. If you have three healthy oscars living peacefully together, consider yourself lucky.
Tinfoil Barbs (Barbodes schwanenfeldi) * 180 Gallons: This is a large (about 12 inches SL) schooling fish that my oscars pretty much leave alone. I have kept a trio of them with my oscars for a little over a year. I would recommend a minimum of 3 for their comfort, so you would need a fairly large tank to keep them with a pair of oscars. My tank is a 120 gal, and is virging on being too small for the two oscars and 3 tinfoils.
Tin Foil Barbs are a hazardous choice. If you decide to go with these guys, you’ll need a large tank. I recommend a 6ft tank bare minimum. Tinfoil barbs can and do exceed 12 inches in length. They are also very active fast swimmers that, like the others, prefer to be kept in groups no less than 3. These fish grow fast, but when they are young, could easily be eaten by an adult oscar. Be wary of this choice in dither fish.
Giant danios (Devario aequipinnatus) ** 75 Gallons
Giant Danios are another decent choice for dither fish. They are small, but very fast. They are also schooling fish and due to their small size should be kept in a larger shoal. I recommend no less than 6. Danios are definitely on the menu for oscars but their speed is what keeps them alive… some of the time. Don’t be surprised when a few disappear here and there.
Silver Dollars (Metynnis hypsauchen) ***** 75 Gallons: These are medium sized schooling fish from South America. They come from similar water types as oscars, and seem to be tolerant of a wide range of water conditions. They are pretty shy, and do best in schools or 5 or more. Since they get fairly large( up to 8 inches ), they need a bigger tank for a school. I would not keep them in any tank less than 48” long, as they are fast swimmers, and need a lot of room. My oscar largely ignores the silver dollars, but even if he wanted to pick on them, they are way too fast for him. They should be fed primarily vegetable matter, and mine love to eat algae wafers. They will eat anything, and often sneak up and steal some of the hikari oscar pellets.
Silver Dollars are good candidates for dither fish. Their unique body shape prevents them from being eaten even at a small size, and their thin body profiles keep their addition to the bioload of the aquarium minimal. Silver dollars find comfort in numbers so keeping them in shoals of less than 3 is not recommended. They are active swimmers and compliment the slow moving/lurching of the oscar.
Spotted Silver Dollar (Metynnis maculatus): Temperament: A South American vegetarian species, also a peaceful schooling fish so keep 3-4 together for their well being. They are hard on live plants but are known to dislike Java Fern and Java Moss to some degree so they may be safe – but no guarantee. Water Quality: 75-82 degrees, neutral pH (can tolerate neutral to acidic). Food: Flake or pellet with vegetable based supplements or actual vegetables (zucchini and romaine lettuce). They also like shrimp and worms, both frozen and freeze dried. – dvross
Bala Shark (Balantiocheilus melanopterus): My tank: They have been in the same tank for almost 6 months now with no issues. The Oscars and shark where 3” at the time they where added to the new 100gallon tank. The O’s have grown quite quickly and could easily give the shark a LOT of issues if they wanted to. But there have been NO issues at all; they don’t seam to bother the shark at all. Generally though the shark is smart enough not to bother the O’s either, generally swimming away when the O’s come around. I have loved having this fish in my tank, just ads some extra something in the tank to look at. Conditions: about the same as Oscars. Food: They love blodworms, but have been doing well on leftover form the Oscars pellets. They will eat almost anything edible. Temperament: a fairly timid fish, prone to darting rapidly around the tank if startled, and they tend to get startled quite easily by sudden movements. They are very peaceful and get along well with other species. On the odd occasion, they may briefly chase another fish around, almost playfully, or if it is annoying them, but never anything more. Size: Supposed to attain a maximum length of around thirteen and three-quarter inches. So these fish get as large, if not larger, than an Oscar. So these should not be used in anything but the largest of tanks.
Common pleco (Hypostomus plecostomus): A great compliment to an oscar tank. Note, however, that as a pleco gets bigger, so does its waste. Do not place a pleco in a tank because you think it will magically make your tank clean. This simply will not happen. Because they are quite agressive toward others of their species, do not place more than one pleco in any but the largest tanks. Also, if your oscars begin to breed, you should remove the pleco. They love caviar.
The Common plecostomus has got to be one the most purchased fish in the hobby today. These fish are purchased with the mindset that they will “clean your tank”. Don’t be fooled folks. Most plecostomus are more messy than your average fish. They do eat algae that grows on the sides of your aquarium, but they also create a lot of waste and add a large portion to the bioload of the tank. There are two species of plecostomus sold as “Common Plecos”: Hypostomus plecostomus, and Pterygoplichthys gibbiceps. The H. plecostomus normally max out around 12 inches, while the P. gibbiceps grow to 18-20 inches. Either way you look at it, these are large messy fish. Even though they may live peacefully with an oscar, I would avoid these fish, especially if you only want one to clean the tank. Those who choose the common pleco should be prepared to do heavy, frequent water maintanence.
Clown Loach (Botia macracanthus): A very discriptive name for one of my favorite Indonesian bottom dwellers. They grow to a maximum length of around 17” in the wild and typically 6-12” in captivity, live as long as 20 years and are most happy in larger groups. Keep at least 3 but 5-7 are preferred if you have the room. They are very peaceful fish and are alot of fun to watch. They will actually play “dead”, laying on their sides or upside down! It is said that you can sometimes hear them making a clicking sound which I thought I’ve heard on occasion, but won’t swear to it. Requirements: They need a large tank, 90 gallons minimum and 125 gallons preferred. They like alot of hiding places so give them plenty of rocks, caves, etc. They are “snufflers” so they like a softer substrate to allow them to root around for food. Temp: 77-86. pH: Not specific, can tolerate a very wide range (They are even good tankmates in African setups.). Water hardness: Softer is preferred. Food: They will eat darn near anything from pellets to plants to frozen foods. Use caution with certain medications. Make sure they are safe for scaleless or ‘ornamental’ fish. – dvross – Added by ksb: I second clown loach. In my experience they are excellent tankmates for aggressive fish. They can get bullied and pushed around but they don’t care. In the end, they usually get ignored. However, they get ich easily.
Pictus Catfish (Pimelodella picta): I’m currently keeping three Pictus Catfish as Oscar tank mates. There’s a lot of conflicting information about pictus….according to sources I’ve found on the net, they can grow anywhere from 4 inches up to 10 to 12 inches. The more common numbers I’m finding is around 6 or 7 inches. This is probably also due to there being two different variations of pictus catfish….a Columbian variety, and a Peruvian variety…….one of which grows bigger than the other. As far as care, they do very well just cleaning up after my O’s….in fact sometimes I’m surprised at how fast they clean up the left overs…..and they really get to flashing around the tank when they do this. On occasion, I do give them some jellied blood worms….and one of them has even learned how to go to the top of the tank and eat whole pellets!!! They also seem to be somewhat hardy, as I recently had one that swam headfirst into the python while it was laying against the gravel siphoning. I was working at the other end of the tank when I noticed him. Well, his mouth was sucked up against the smaller part of the tub inside the large gravel cleaning tub, so much so when I turned the python off I had to shake it to get him un-stuck. Well….somewhere in the process he lost literally half his tail, and all the way around his mouth was red from blood under the surface of his skin from the suction. That was on Sunday, and he’s doing fine….tail is already starting to grow back, and all the redness around his mouth is gone. Environment wise, they do well in the same temp of water as my O’s, and prefer pretty much the same water parameters as O’s. That’s part of the reason I went with them…..both species were from South America.
Pictus Cats are a dangerous choice. Spotted pictus cats are probably the most readily available catfish in big chain stores. They are active swimmers and good scavengers but prefer to be kept in groups. Their relatively small size (5 inches) is what makes them a gamble with your oscar. Eating a pictus cat might be your oscars last mistake. Both Spotted and Four-line pictus cats have bony pectoral protrusions that they use for defense. Not only are they sharp at the tip of the bone, but they are also jagged on the anterior surface making it extremely difficult to remove should this weapon punture any tissue. I would say that the Four-line pictus is a safer choice as they grow to 8-9 inches in length, but still their long thin bodies make them a target for determined oscars.
Raphael catfish (Agamyxis pectinifrons/Platydoras costatus ) *** 75 Gallons
Raphaels are another option as a tankmate. Striped raphael cats can grow to 8 inches, and Spotted raphael cats grow to 5 inches roughly. Both of these cats have hard armored bodies that deter most predators from eating them, and I would say this is true for oscars as well. The downside of both Raphael cats is that they tend to be very nocturnal. They hide for the duration of the day, and really are only active when the lights are out.
Synodontis eupterus (Featherfin Syno) **** 75 Gallons
This is one the most overlooked catfish available in pet stores. They are a peaceful species that reach 8-9 inches in length. This is one of the most compatible tankmates for large cichlids as far as the common catfish is concerned.
African Brown Knife (Xenomystus nigri?): I’ve had an African Brown Knife with my first Red Tiger O for about a year and with my second Red Tiger O (bought at 8”) for about 4 months. Both O’s totally ignore the Knife unless they have eggs, and then they chase him off if he gets close to the eggs when he comes out of his cave. The Knife is a nocturnal scavenger, and needs a place to hide during the day and/or when the lights are on in the tank. I bought a piece of fake wood from Petsmart that’s hollow on the inside with a hole in each end – the Knife immediately took up residence in there. My Os also like to sit on the bottom behind the same piece of fake wood, so it works out pretty well. If you have a breeding pair of Os I’d recommend removing the Knife when your O’s have eggs. They like the eggs and I feel sure they would eat the fry as well. I personally choose to remove the eggs after they are fertilized (I have a plec in the tank as well). – MattR – Note from Saluki: These fish can get over 2 feet long. Only buy them if you have the space to keep them.
Other Possible Options
Tetras, and other large Barbs can also be used as active tankmates. However, you must choose these fish as Oscar tank mates with caution. Some oscars will eat anything they can fit in their mouths, and some would rather not have to chase their food. If you have the latter, then large barbs, and tetras may be considered as tankmates. Buenos aires tetras, Black skirt tetras, Congo tetras, Diamond tetras, Rosy barbs, and Gold barbs are all good choices. Again, don’t be surprised if they do start disappearing.
Catfishes and plecostomus are also popular oscar tankmates. Some make excellent tankmates as they are scavengers that eat any left-over food a messy oscar may have left behind. Others are not great choices because of their large adult size. Due to the differences in body shape, catfishes are rarely looked upon as threats by most cichlids. And their unique look adds that extra bit of extraordinary to an otherwise normal aquarium.