Correct sentence (simple):
Moray eels hide among corals and grab any small fish that swims by.
Other good options:
- A moray eel hides among the corals and grabs any small fish that swims by.
- Moray eels hide in crevices between coral heads and grab any small fish that swims by.
Why this is correct (easy steps):
- The original sentence is mostly okay, but we can make it a little clearer. For many corals, we usually say "among corals" instead of "between corals." Use "between" when you mean two things; use "among" when there are many things.
- "Moray eels" is plural, so the verbs "hide" and "grab" are plural and match the subject. That is correct.
- "Any small fish that swims by" is fine. The word "fish" here is thought of as one fish at a time, so "swims" (singular) is correct. You could also say "any small fish that swim by" if you think of fish in general (plural), but the original "swims" is natural.
- "Little" and "small" both work. "Small" sounds a bit more natural here, but "little" is okay too.
If you want, try saying your sentence out loud and pick the version you like best!