Jim, Here's what I use, works great and it's a protein transformation not raw fish...
3 pounds White Firm fish - Trigger,Cobia, Wahoo, Mako, etc.. I've used Snapper (black is better then Red) FRESH never frozen
1 cup lime juice
1 cup lemon juice (for lime and lemon - I buy best quality bottled) like Reallime (read the back no sugar added or preservatives.
1 cup peeled, seeded and finely chopped cucumber
1 seeded and finely chopped large tomato
1 seeded and finely chopped yellow bell pepper
1/2 cup chopped fresh cilantro
1 finely chopped large sweet onion
3 smoked dried chilli peppers ( I do my own)
1 tsp Kosher salt, for seasoning
Chop fish into 1/2"x1/2" (or smaller) cubes, add to 1 Gallon strong ziploc bag, pour in lime and lemon juice, agitate then refrigerate. Work on the veggies and peppers - add peppers after first hour. Agitate bag and fish once per hour for 3 hours (done after one hour if in a hurry... or late) pour off about half of juice more if you want but leave enough to fully coat veggies, then add veggies. Agitate and sit for one hour - if you can. Spoon out about what you can eat into a bowl and have at it - will keep for about 2 days def better day 1. makes about 4-5#'s Ceviche.