Measure out the butter, cut up, and add to a medium-sized bowl to bring it to room temperature.
With rubber gloves on, remove seeds and membranes from chilli; mince. Mince the shallot. Grate the lime zest. Add all to the butter, along with the salt and fresh lime juice.
Use a hand mixer to combine the butter and other ingredients.
Remove herb butter from the bowl onto a layer of plastic wrap; divide in three. Put each third on its own piece of plastic wrap, and then into a small plastic zip-lock bag; write on date. Chill or freeze until needed.
When needed, bring the butter to room temperature and serve on top of plainly cooked tilapia fillets, or striped bass fillets, or melt the flavored butter and use to bake the fish according to the directions in Tilapia in Citrus Peel Butter.
Epicurious: Pan-Seared Tilapia With Chile Lime Butterhttp://macheads2.net/recipes/ChileLimeButter.html