Backyard Aquaponics
A place to discuss aquaponics

I Trying to find out if Fresh water fish such as Trout could eat crushed saltwater green or rock crabs for feed? I Suppose i could soak the salt out of the crushed meat if necessary if that would help. I've Googled this a dozen different ways but no answers found yet.

soaking or mixing with another ingredient may be a good idea, or just draining off fluids from inside the shell, ie. only feeding the solid muscle meat.

In reality this should not be a problem at all, as far as my theoretical understanding goes. Both fish and crabs have the ability to osmoregulate. This means that the body fluid/blood of freshwater fish, eg trout, is "saltier" than freshwater, and that of marine fish (and crabs) is "less salty" than seawater. So the difference between the saltiness of the crab meat and that of the trout's body will be much less than the difference between seawater and freshwater.

Furthermore, trout have the ability to osmoregulate in seawater (at least to some degree), and the gut is a key organ in the process of osmoregulation so should be able to deal with varying salt levels in food; it may even be beneficial to them, as freshwater fish absorb "salt" from their food efficiently in order to maintain their own osmolality (salt levels).

I fed baby shrimp from the sea to goldfish once, with no issues.

If you do use them, it should be supplementary to a formulated feed, or part of a more varied diet.

Try to get a second opinion though

Yeah i am trying to reach the State Agriculture Dept. to see if they even have a "expert" on staff. I'm thinking that the useless green crab and rock crabs might be good for formulating a natural food product for aquaculture operations. They would be protein, nutrient rich and there should be a freeze dried or dehydrating process to preserve the product for shipping etc,. I'm in a remote area of Maine but we have seafood access like crazy. I'm thinking about the old saying, "build it and they will come", i just need some more research for alternative food options to cut down on buying feed and paying those freight/shipping charges that would eat into profits, or at least beat the hell out of my fun.

The crabs aren't useless they are part of an intricate web of biodiversity, and being that they are in the change zone from land to sea, they are pretty significant.

my oscar in my indoor tank loves when i bring spidercrabs home from the beach for him.