As with most animals, it is best to give your gerbil and reasonably varied diet, which is also high in nutrients. Gerbils can be fed seed mixes or block feeds, which have definite differences. Seed mixes, while providing for a nutritional mix if fully consumed, allow for the gerbil to possibly pick out their favorite bits and leave the rest. Also, if the seed mix is heavy on sunflower seeds (which are quite fatty), the gerbil may just feast on these and ignore the other seeds, which provide the nutritional balance. On the other hand, lab blocks and pellets are all in one piece, and don’t allow for such selectivity, and have some scientific evidence behind them for nutrition. However, lab blocks and pellets don’t really have much variation, and so could bore the rodent. The best solution is to give the rodent variety while still providing good nutritional content. Thus use seeds in a controlled way, possibly picking out the sunflower seeds to use as treats and in training, and use the block and pellets as the main source of nutrition.
The amount of feed given to a gerbil is also important. A routine should be set up to feed the gerbil every 24 hours, approximately at the same time. Night time is quite good. Place the block or pellet in a ceramic or heavy plastic bowl, with the supplement on the side. Try to get a feel for how much the gerbil will eat within a day, and then keep on feeding that amount. Try not to give too much to avoid spoiling within the period. Remove any uneaten food from the previous day before feeding. Feed any treat food in a separate bowl and remove after a couple of hours to prevent spoiling. Alternately, you could hand feed the gerbil, which would instill trust in the animal, and provide a solid base for training outside the cage.
Although gerbils are small, they still require a fresh water supply to maintain their internal organs. This water should be replenished regularly into a bottle sipper. Try not to allow the water to get stale.