What can you tell me about the Rio Grande Valley cichlid (a fish)?

Question

We saw a school of them with rainbow-like colors, "digging" and fiercely protecting holes in shallow water, where they might have been laying eggs.??

Answer 1

Yep, that sound like classic spawning behavior all right. These fish are also called Texas cichlids. Here's a good link about them.

http://www.wetwebmedia.com/FWSubWebIndex/texascichlid.htm

MM

Answer 2

Also known as the Texas cichlid...very pretty fish. They get up to a foot long. One fish requires about a 50 gallon tank with a sand substrate as they like to dig..as you found out :)
It's difficult to tell males from females until they're a bit older and then the males get a nuchal hump (an enlarged bump on their forehead area).
They spawn on flat rocks, not in holes. They just like to dig...laugh..and they're protecting the holes as they are taking ownership of a territory.
They're not the greatest of the cichlid parents. They tend to eat their fry after diligently guarding the eggs suspended upon the flat rocks.
They are considered aggressive fish and need to be kept in large tanks with other aggressive cichlids.