substitute for snakehead fish
Here is an article in the Washington Post on a local caught taste test for snakehead:  https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/05/20/snakehead-taste-test-can-a-fish-this-ugly-really-taste-that-good-photos/?utm_term=.6ff5bd89c114

They compare snakehead directly to cod, tilapia, and flounder and indirectly with catfish cooked in various ways, in general comparing it favorable with each, a bit firmer than cod or tilapia.  Though I have not had the opportunity to have snakehead, this is consistent with other reports that I have had which list it as similar to catfish, usually reported as a bit cleaner or milder flavor.  Similar flavor and ability to grab spices to tilapia, but a firmer texture that holds up to cooking.  I would think that catfish or maybe mahi-mahi would be candidates for a curry for their ability to stand up to a bit extra cooking while candidates like tilapia tend to be thin fillets and soft so may well not stand up as well.