Fat-tailed gerbils do not have a complicated diet for an exotic rodent, and in fact does not differ that much from a Mongolian gerbils. As with any animal, preferences will not be the same for each individual so it is important to ensure you are offering your Duprasi a variety of foods.
Duprasi do not drink a great deal, but water must be constantly available. Bottle or bowl is fine for this although the later should be checked and changed frequently as it may well get buried.
A normal hamster or gerbil mix forms a good base mix for a Duprasi's diet. Gerri Gerbil is a good mix we use for both Mongolian and Duprasi. Alfalfa pellets can also be given.
Duprasi's natural diet would include a sizeable array of insects so a captive diet should do their best to include this. Crickets and mealworms are a good inclusion, either live or dried. Another good addition is an insectivore mix such as Bogena Universal.
Scrambled egg is a good fresh source of this. Dry cat food is another option and some keepers also supply rodent blocks.
Your Duprasi will appreciate small offerings of most fruit or vegetables. These should not be given daily and care should be taken to ensure your Duprasi does not have large amounts of water in their diet since they are not naturally equipped to process a lot of watery foods.