Disclosure: A mandarin fish can be difficult to keep and is not considered a beginner fish. Pellet training does not happen overnight, and may never happen with your fish. Also, it should be noted that although many people call them mandarin gobies, they are actually in the dragonet family and not related to gobies.
1. Before you get your mandarin fish, you’ll need a Fish Net Breeder. It’s essentially a box with fine net, you can get it at many local pet stores.
2. Also, make sure you have access to live brine shrimp before you begin pellet training, and I would also recommend picking up a bottle of Selcon. Selcon is a vitamin supplement for fish.
3. Assuming the tank is set up and is a stable environment, place the net in the tank making sure it stays at the top and will separate the mandarin fish from the display tank.
4. Before the mandarin will eat pellets you need to get him eating something other than pods, and an easy switch is the live brine shrimp. Brine shrimp on there own aren’t very nutritious, which is why I would recommend enriching them with Selcon. To do this have the brine shrimp in a separate container and add a few drops of Selcon. Leave them for a couple hours and you’ll notice the water go from cloudy to, less cloudy. This means the brine shrimp have eaten the Selcon which now makes them super nutritious when the mandarin eats them. You could actually feed your mandarin enriched brine shrimp if you are unable to get him onto frozen or pellets and he would live a happy and healthy life, it just becomes expensive and can be a pain to feed.
5. Once the mandarin fish is eating the live brine shrimp, should take minimal effort on your part, you can begin slowly introducing frozen brine shrimp. The key to tricking your mandarin is leaving the water pumps on while feeding him in the net, this way the live brine shrimp and pushed up against the net, along with the frozen ones. I would recommend soaking the frozen in Selcon as well to give them a similar taste.
6. When your mandarin fish begins eating frozen brine shrimp you will want to wean him off the live brine shrimp until you have him eating all frozen. From there you can slowly introduce other frozen foods, like mysid shrimp. Making sure you are soaking the different foods in Selcon helps trick the fish with similar scent and taste.
7. To make the switch to pellets it’s a matter of introducing something that is similar looking to pellets, and for that you need ROE, also known as fish eggs. While these aren’t the easiest thing to come by, you can sometimes find them at an Asian Market, or you could pick up a bottle of Dr. G’s Caviar Max. Make sure to soak them in Selcon just to make scent and taste similar.
8. When your mandarin is eating the ROE, the next step is introducing pellets. Soaking them in Selcon for a minute should help with tricking the mandarin. You don’t want them to get mushy. I use Formula One Pellets when feeding my mandarin. When you see your mandarin eat a pellet for the first time, it’s a great feeling.
9. Once the mandarin is eating the pellets you shouldn’t have to soak the pellets in Selcon, although you can for extra nutrition or if you notice the mandarin not eating them.
At this point you can release your mandarin in your display tank. Unless you have a species only tank, you may need to find some way of feeding your mandarin the pellets without the other fish eating them first. Melevs Reef has a great resource in how to make your own mandarin diner.
If you are struggling to get your mandarin to eat frozen anything, sometimes squirting frozen food in a small clump of chaeto can trick the mandarin. With getting them to eat new foods, it’s all about tricking them. Mandarins are very finicky eaters, and in the wild typically eat live copepods for a majority of their diet. Once they start eating something though, they usually will continue. Also, frozen bloodworms may work as well if you are having trouble getting them to eat.
One other thing that has worked for me in the past, is getting an eye dropper and getting the mandarin to recognize it as where food comes from. Starting with live brine shrimp helps, and make sure to squirt them out slowly. Eventually, over weeks or more, the mandarin will eat directly from the eye dropper and from there you can sneak in various other foods.