I wouldn't recommend either zebra danios or pristellas for a 10 gallon tank.
Stocking these small tanks is difficult, and 10 gallon tanks should be avoided by beginners. The problems are multiple. Small tanks experience dramatic changes in water quality and especially water chemistry that inexperienced hobbyists simply can't handle fast enough to avoid fish sickness or death. Small tanks don't hold as many fish as inexperienced hobbyists think they will, causing problems with overstocking and under-filtration. Small tanks lack adequate water volume to tolerate power outages or periods where they are unattended, e.g., vacations. Installing lighting sufficient to maintain plants is very difficult, and without healthy plants, algae problems tend to be a major headache. For the beginner, tanks 20 gallons upwards are, in my opinion, the absolute minimum.
Zebra danios get quite big, are hyperactive, and in small groups can be bullies. A "long" (60 cm) 20 gallon tank is about the minimum sensible size for zebra danios, and in such a tank you can install the strong filter they need, giving them plenty of exercise. You can keep a school of 6-8 specimens easily, and in such numbers they'd not be likely to bully or nip each other or other types of fish.
Pristella tetras could be crammed into a 10 gallon tank, and being hardy and peaceful wouldn't do much harm. But they'd never look that good either, and would certainly be at risk from all the problems mentioned above.
Stocking 10 gallon tanks is an art form, and one I've written about in, for example TFH Magazine and on
Wet Web Media. You need to choose small (sub-4 cm) schooling fish that aren't active, such as neons and
Corydoras habrosus, or else go for larger fish that don't need swimming space, such as kuhli loaches and small whiptail cats. Shrimps and snails are generally very good additions. A combination of 6-8 neons, 5-6
Corydoras habrosus and a few cherry shrimps is an ideal collection of livestock that would work well in a 10 gallon tank.
Cheers, Neale
