The Shedd Aquarium has nice site on fish found on a Caribbean Reef.   It’s very visually attractive, and the explanations are in fairly simple English.

I’ve placed the link on my English Themes For Beginners page at the bottom of the Animals category.

I learned about this site through Techlearning, which also has an educational “site of the day” feature, though they aren’t necessarily accessible to English Language Learners.