Thanks to ADHD, I don't have the concentration needed for pro looking sprites, so I had to develop my own style.
[snip]
I'm pretty proud with this.
Hope I don't drag this on, but I probably will toss some terms around.
The lines need to be cleaned, they're very jaggy, and the sprite itself is pretty noisy and not very readable, but that's the fault of the 2-bit palette which is a challenge that, frankly, can't be handled easily. (Don't dither, that probably wouldn't help.)
I'm assuming those things on his back are spikes, in which case they're very uneven and rushed. (Your ADHD may prove as an obstacle in trying to fix them.) Or they could be fins, which gives them an excuse. Actually they seem to be a mix between the two; they come in a strange variety of triangles and blobs trying to be triangles. The blobs on his body are clearly sort of fins (although cylindrical lighting seems to suggest otherwise), however, so you have an example of what are fins and what are not. Looking back though, I don't ever remember seeing fins like that on a real fish. And don't say it's because this is a fish that doesn't exist.
Also, protip, it's recommended you don't develop your own "style" at a stage without much skill. (Right now you seem to be decent, though, so that's good.) A lot of faults can be passed off that way (just look at amateur manga artists on DeviantArt--some of those are textbook examples of this sort of thing), but it doesn't usually pass through the eyes of the skillful, and keeps them from improving at a significant pace--that is, if they do keep passing it off. Considering your condition, perhaps work on it through short intervals?
Edit coming soon. Already started.