Before I moved I had an outlet from the kitchen that had a GFI,
but now I don't have a GFI protecting myself or my aquarium's life.

Recently I had some water slowly trickle down a cord into my power strip.
Nothing happened other than a short, plus a wreaked power strip,
but I want a GFI so I don't fry myself if soemthing wasgoing to happen.

Do I need to go with one that you install into the wall or will an external one be reliable enough and not randomly trip ?

external ones are fine.

I used an external one for years with no issues.

External are fine, I used to use them too. The only downside to them verses in-wall ones, is that they are much more sensitive. If your power goes out, 9 out of 10 times, the external GFCI will trip OFF as soon as the power comes on. Happened with both of the ones I had everytime the power went out. This is bad news if that happens say while you're away at work... =/ Other than that, they will work just as an internal one. Good luck!!

Okay I can live with that,
I have a big enough family that somebody is almost always home.
Thanks for the suggestions and help.....

No problem! Just thought I'd point out what to possibly expect with it so you're prepared.