I am sorry to disappoint you, but imho you got 3 male GBR. The yellowish one looks not very fit with that sunken in belly. For how long have you had them? I would try to get 3 female GBR. You could also add Bolivian rams. But those are larger and would dominate the GBR. Personally I would stick with one species.
Btw do you know your water parameters. What are KH & total hardness? GBR should only be kept in soft water. Read here about GBR:
http/www.seriouslyfish.com/species/mikrogeophagus-ramirezi/
The guy at the LFS said he thought they may have been male/female of course he would say that though because I bought them quickly haha I know the washed out one is a male, he use to be a lot brighter and healthier a couple months he started going downhill. I've had him for about a year I would say now. He was my first ram and he paired with a female I had. I assumed they took out the third ram because I found him dead but no signs of bad water or anything. Then months later my female went missing and my male started to lose color. I figured out that my boyfriend's red tail shark was constantly chasing the rams and harassing them a lot, especially at night. I think he may have killed the female ram since she was so small and my red tail shark was about 6 inches or so. I decided I was going to get rid of the shark but then couldn't find the male ram so I assumed he was dead. Turns out he was just hiding really well and when I found him he did not look good at all. (tattered fins, sunken stomach, pale etc) I took the RT shark out a couple days ago and picked up the two new rams.
Since I've added the new rams the old ram's color has brightened up a lot compared to what it was but he still resembles more of a bolivian ram with his lighter colors now. I don't know if his coloring will ever come back. I think he was hiding behind my 3D background which is completely darkness and a tiny space for him.
One of the new rams seem to be doing a lot better than the other two. Bright colors all the time. The other ram (one of the new ones) follows the alpha ram around the tank but when he/she does the alpha ram usually attacks it or displays. Sometimes they follow each other around and are perfectly fine.
PH is 7.0 and I am not exactly sure of the hardness of the water in my area but I've never had problems keeping rams before.
Is there a separate kit to buy that will just test hardness?