[Updated 05/05/2023]
Cichlids are a diverse group of fish, comprising many, many, many species. And, many of these cichlids unfortunately have very similar names, which can make it confusing. This article talks about two species that are commonly confused, the texas cichlid and green texas cichlid, along with their derivatives. The care and other aspects of keeping these cichlids are not discussed, this is just to help differentiate the many 'shades' of 'texas' cichlids.
Texas cichlid
The texas cichlid refers to Herichthys cyanoguttatum (or Herichthys cyanoguttatus, depending on who you talk to). These cichlids tend to have smaller, rounder, more regular pearling on their body, often in a very regular pattern, and often do not have worming (squiggly patterns) on their face. Their color tends to be less vibrant. These are actually pretty rare in the hobby.
Green texas cichlid
The green texas cichlid is a whole other species on its own, Herichthys carpintis. They do belong to the same genus, hence do have some similarities - adding to the confusion. This species is also known as the 'rio grande' cichlid.
Green texas cichlids contain more vibrant, irregular pearling of all manners of shapes that are spread in more irregular patterns. Some variants can have wormings on their faces. The color of their pearlings tend to be a clear shade of green or blue, hence their name.
Some green texas cichlids have particularly vibrant coloration and patterns, and are referred to as super green texas cichlids (SGTs). The fish pictured above would be considered a SGT. The most famous collection locality for SGTs is Escondido, but fish from other localities like Chairel and so on are also often SGTs. Nowadays, SGTs are very common in the hobby. There is another name that they are often referred to, the 'electric blue texas cichlid', likely a marketing tactic to compete with electric blue jack dempsey cichlids. However, SGT is the older and more common name that is used, at least by cichlid keepers in the hobby. 'Electric blue texas cichlid' is more commonly used by fish stores.
Blue texas cichlid
This is a particularly confusing name as it is used to refer to both texas cichlids (H. cyanoguttatum) and green texas cichlids (H. carpintis). Therefore, the term is not very commonly used, at least in the hobby by cichlid keepers. It is used quite often by fish stores though.
Red texas cichlid
This name refers to hybrids (and descendants) of texas cichlids (H. cyanoguttatum), green texas cichlids (H. carpintis), or a descendant; and other cichlids to introduce a red coloration to the progeny. Therefore, they are not a naturally-occurring fish. It should be noted that usually, the 'red' is of the basal body color rather than the pearlings, which can range from white-ish color to a green/blueish tint.
There are some additional terms that are used to describe these fish. 'Failed red texas cichlids' are often referred to these fish that do not actually get red coloration or nicely patterned/colored pearlings.
'Super red texas cichlids' refer to red texas cichlids with particularly vibrant colors and patterns.