hm... well, let's see...

i dont quite remember my first, sicne ive had tons of pets come and go, not to mention fostering dozens every summer... here's my list, as far as i can remember:

fish- lots (i have an outdoor pond with tons, maybe in the 20s) my whole life
cats- i have 3 current, and 2 that have passed away.
turtle- one, not anymore, named fluffy and we fed it hot dogs
hamsters- 2 albino when i was small (dont remember where they went) and then 3 later on (now deceased)

...and i think that's all. my first et must have been either my first two cats or the albino hamsters.