How to Make Fiddler Crab Food
To make your own fiddler crab food out of fish food, combine equal parts of at least 2 different types of fish food, like flakes, pellets, dried bloodworms, or brine shrimp. Add in a little drinking water until the mixture is thick and soupy, then pour the mixture into small ice cube trays. Freeze the fiddler crab food for at least 12 hours. To feed the crabs, put a cube under the sand and wait for it to melt. The crabs will be attracted to the scent and will eat the food as it thaws.
Gather a batch of soft vegetables like squash, zucchini, or several pieces of leaves of lettuce, spinach, or celery leaves. If you can, get organic veggies to reduce the possibility of feeding your crabs pesticides. If you are unable get organic, regular is still acceptable. Scraps of vegetables, if not contaminated with raw meat or other substances, are a great way to use otherwise trashed food. Just make sure they aren't rotting. Wash your veggies! Use special vegetable wash, not regular soap, or make your own. Combine a cup of tap water, a tablespoon of lemon juice, and two tablespoons of white vinegar to use as a soak or spray-on type of wash. Soak for ten minutes, then rinse. Washing is especially important for those using non-organic food. Tougher types of vegetables can withstand scrubbing; but, some leaves are too soft for this. If you get pre-washed, organic vegetables, you can skip this step, unless you want to wash it. Non-organic vegetables with skin should be peeled and washed, as much of the pesticides are found on/in the surface. Shred your vegetables. For big vegetables like zucchini, dice up the flesh into tiny pieces. Each shred or piece should be no bigger than your pinky nail. Soften your vegetables. In a microwave safe container, microwave your vegetables in some purified drinking water for a minute. It is important not to use tap water so that chlorine or heavy metals aren't ingested by your crabs. Use small pieces of vegetable so that you don't have to microwave them for a long time. Let the vegetables cool down. You can drain the water off (be careful if it is hot), put the solids in a plastic bag, and stick it in the freezer for a maximum of fifteen minutes. Feed your crabs! Stick a few shreds into the water (you might have to stick them in the sand or in a bowl if the pieces float around) daily and replace daily. Freeze any extra for later, and thaw them by microwaving for thirty seconds. Start out with washed produce: You can use leaves or soft fleshed vegetables. Put all of your vegetables in a blender. Add a cup of drinking water for about four cups of vegetables. Pulse on and off frequently to avoid making veggie soup. You should have visible shreds of vegetable floating in water. If you are using thick vegetables, you might want to cut them into smaller pieces before blending. If the ratio of water to vegetable shreds is high, take some liquid out and strain out the solids, then add the strained vegetables back into the blender. Freeze your vegetables. When you have blended up a nice, non-soupy mix, use ice cube trays to freeze small portions of this vegetable blend. Freeze for at least 12 hours. Use the cubes to feed as a time-released diet for your crabs. Splitting a cube in half for smaller tanks is good, so you don't waste food. Stick a cube in shallow sand daily; it will melt and the crabs will be able to sift through the sand to find the food. Obtain fish flakes (any kind), pellets, dried bloodworms, or brine shrimp. Since fiddler crabs are omnivorous scavengers, any fish food will be good. If using, soak dried bloodworms, brine shrimp, or pellets in some tank water until softened. Combine your ingredients. It's best to use a combination of at least two foods to provide variety and nutrition. Mix with drinking water until you get a slightly thick soup. Pour your mixture into ice cube trays. Freeze for 12 hours. You might want to use smaller ice cube molds, because this method packs quite a lot of food into a cube. Feed! Using the same method as the vegetable cubes, putting cubes a bit under the sand and wait for them to melt. Crabs will be more attracted to this kind of food, as non-vegetable food sources give off more of a "there's food here" smell that crabs can track. 
Gather a batch of soft vegetables like squash, zucchini, or several pieces of leaves of lettuce, spinach, or celery leaves. Wash your veggies! Shred your vegetables. Soften your vegetables. Let the vegetables cool down. Feed your crabs! Start out with washed produce: Put all of your vegetables in a blender. Freeze your vegetables. Use the cubes to feed as a time-released diet for your crabs. Obtain fish flakes (any kind), pellets, dried bloodworms, or brine shrimp. Combine your ingredients. Pour your mixture into ice cube trays. Feed! 