either will work just fine. I've used both and see no difference in either. You'll be fine with the regular Krylon outdoor/indoor kind. Like others have said wash with running alcohol let dry and spray away.
Nice and easy will win the race here. Go slow and take your time. Plenty of ventilation and cover as much surface area as possible around where your going to spray. Let dry, inspect and repeat until fully covered.
You may have to pull back the front and look through so you can see any missed spots. It's harder to tell from the backside.
Your doing this with fish in so I can't stress enough to make sure the top is covered well and make sure not to get overspray on the filters etc...
Start from the top and just go light back and fourth, left to right or right to left. You get the idea.
Just take your time. You don't wanna run into a drip session that will stink! So watch the top and make sure it's dry before you reapply. I've noticed after doing several tanks the paint WON'T stick to the top area where the silicone is, as well as the rest of the tank.
You'll be fine. Take your time.
And post some pics!