Who Dat...Mekong Tiger Datnoid

Welcome to today's round of “how on earth do I pronounce that?” The fish in question, (Hey, you're on an aquarium website, of course it's an aquatic critter) is Datnioides undecimradiatus. Luckily for all of us, most aquarists just call all the Datnioides: “Dats.” This is a very cool genus of fish, and all of the fish included in it feature another difficult to pronounce feature, a protrusible mouth. This means they can extend their mouth parts outwardly to help them suck in prey. This exceptional talent, along with their cool body shape, generally peaceable demeanor and large size, all make them a favorite among freshwater aquarists who like to keep big fish.

These are relatively rarely seen in North American aquariums, but frequently seen in the fish markets of Thailand, Cambodia, Vietnam and Laos. They're found in the lowermost reaches and deepest parts of the Mekong River and its tributaries but are generally believed to stay out of saltwater. In the US, this fish is usually called the Mekong Tiger Datnoid, but you'll also frequently see it marketed as NTT or Northern Thai Tiger Fish. Less often you'll see it called Siamese Tiger Fish and Gold Dat, but another fish in the Datnioides genus (Datnioides pulcher) also shares this common name, so be sure you're looking at the correct fish when purchasing. In fish markets, it is most often marketed as Tiger Perch (or a regional translation of this.)

Dats grow slowly, but they can get almost a dozen inches long. A much more common adult size is in the eight to ten inches long range. As a result, they're going to need a big aquarium at maturity; somewhere in the range of 100-125 gallons would be good. They'll do better in smaller aquariums when they are under five inches or so, as they can be shy when small, and a smaller tank will make them easier to feed. They like big meals, and we'll touch on that later, but this also means they're going to need strong filtration. Shoot for a filter than can turn the aquarium volume over at least 5 times an hour for example, your 100-gallon display would need a filter that pushed 500gph and up to double that would still be totally appropriate. The display should offer plenty of cover in the way of driftwood, rocks and even plants, but plants might get rearranged. They'll do best in dim lighting, especially when they are small or first introduced. Don't be alarmed if your Mekong Tiger Dats hide, this is normal behavior while they're getting used to a new home. Just make sure they get enough food.

One of the main reasons people love to keep Dats is to watch them eat, but sometimes wild specimens can be picky about what they want to eat, and shy enough to hide through mealtimes if they share a tank with boisterous eaters. In the wild, they'll eat any fish or invertebrate that in unwary enough to get close and is small enough to fit in their mouths. In the aquarium we usually feed them Gamma Bloodworms, Krill, Chopped Prawn, and Chopped Mussel when they are small, larger specimens will eat Gamma Whole Fish, Whole Cockle and Whole Mussel. They can also be fed market fish or prawns. Even the pickiest gourmands among them will never pass up live earthworms or redworms and live feeder fish can also be used if you have a clean source for them that are being fed a nutritious food. We generally get them to eat thawed foods in short order, even if they are picky to start with. It's good practice to keep them on their own until they get used to eating before adding them to a display with lots of other fish. Mekong Tiger Dats should be fed every day until they are four or five inches long, and after that point, they'll do better if fed large meals every other day or every third day. You'll see some people recommending to feed them liver or heart, but terrestrial meat sources can be hard for them to digest, so stay away from this.

Mekong Tiger Dats are good tankmates, especially when they get big enough to be a little bolder. Small specimens will do best when kept in groups of five or more, which will help them acclimate and be more outgoing. Larger specimens can be kept like this as well, as long as they were raised together. Single adults should probably not be mixed unless you have an absolutely massive aquarium as they can be territorial with each other. Other than that, they are pretty much ignore other fish that don't bully them or aren't sized correctly to be called “breakfast.” They are often kept with Peacock Bass, Stingrays, Arowanas, large Catfish, Pacus etc. Think big and think mostly peaceful / graceful.

Like most Dats, your Mekong Tigers will do best in excellent water quality (see the bit on filtration above) and so keep up the water changes. They prefer a slightly acidic water profile, somewhere in the pH 5.8-7.2 range. They are tropical fish but can deal with a pretty wide temperature range, anywhere from 68 to the low 80s. At the lower end of this range, they'll grow more slowly and eat less. They aren't hardness specific and will be fine unless your water profile is crazy out of whack.

Mekong Tiger Dats are probably the coolest of all the Dats. They sport these bold black lines that get thinner as they age, over a silvery grey to burnished bronze body. They're the coolest to watch eat, and your friends are going to encourage you to overfeed them just to watch. Stay strong! If you're looking for a group of really cool fish to fill out your killer big fish display, you need to keep Datnioides undecimradiatus on your radar. Head over to your LFS and ask them about getting you some from Aquatropic today!