Fishymann, you need to make sure that you are adding a detectable ammonia source, and then you need to be tracking the time it takes for the ammonia and nitrite to go down to zero. Ideally, your tank is cycled when you add the amount of mysis you plan to feed your seahorses, and then when you check the parameters 4 hours later, everything is at zero. Eventually everything will go to zero if you leave it without a new ammonia source for long enough, what you want is for the tank to be automatically processing it every time you add it. The bit of shrimp you added may need more time to decompose and add ammonia to the aquarium, so I'd keep watching things for a week or so to see if it is just processing it efficiently, or if the shrimp just hasn't started breaking down yet. Then try the mysis test.