The first four harder than others?? But the Beta (sorry, my keyboard don't have the symbol for it) is the easiest of all, even showing the entire animal. And given that is one of the most common aquarium fish seen in every pet shop makes it easier (in fact this was my first species of fish that I kept ever... Maybe I should buy some once more). So I'm surprised that only Chlidonias gave the correct hint...
The second easier is the E. Very obvious too, diamond firetail, unmistakable!. The others are harder.
Not much things can I add that has not ben said already. Just the J, that is not what has been said. I'm sure it's a bird of similar size (a bit smaller), and also ground-dwelling, but from a different continent and much more primitive... And its the most commonly kept species of their whole group.
For the F, laughing dove and Chlidonias got clearly the correct genus (very different from green iguana). I guess that I know the scientific name, not sure if the common name is just a direct traslation, such as Klemmer's day gecko...
Ah, and I see nobody commented yet on H? It's not just the only pheasant species that got widespread outside Asia and all over the world...? Not sure on this one...
The most difficult for me are the Gamma and the i.
My field are the identifications, I'm too ignorant for trying to see hidden things shared by common names and reasongs for put greek characters

so I let it here.