If your Mandarins are housed with larger, more aggressive fish, they will not get to the food in time. In any event, keep in mind that Mandarins are not big eaters so any additional feedings should consist of small quantities of finely chopped foods. Mandarin fish lack scales and instead have a rather thick, slimy, mucus coating on their bodies. This coating tends to make them rather resistant to parasitic skin diseases. In fact, this holds true for most scale-less fish such as gobies and blennies.
Mandarin fish are one of the few marine tropicals which can be easily sexed.
There are a number of morphological features which can be used to differentiate between the sexes. The males tend to be larger and more robust than the females. The caudal and soft dorsal fins are larger in the male and the male tends to have more orange on it's face. However, the most distinctive difference is in the dorsal fin. The males have a greatly elongated first dorsal spine while females do not.