It's a ram Mikrogeophagus ramirezi, otherwise known as blue ram or German blue (the best ones came from Germany for a long time).
Needs very warm (around 28°C/82°F) very clean, soft water that's low in nitrate.
I have to say, yours dosn't look very happy. Do you know what's picking on it/nipping it's tail? What other fish do you have in the tank?