I have a heavily planted tank with a shoal of cardinal tetras in it and was thinking about adding a pair of German Rams. Do you think the tank size is too small for them?
If the 2 rams do not pair up - and a male and a female ram will not necessarily pair up just because they are in the same tank - one of them will be bullied badly in a 10G.
you never said what a shoal is... I would think either 2 rams, or your shoal. 10 gallon tanks are really nto a home to much fish as there so small. better yet get a 29 and add the two rams and the tetra's .
I would not put two rams in a 10 gallon unless they were both females and even then you could have some aggression issues. If you get a male and female mated pair things will get pretty ugly for the cardinals during spawning periods.
I think 6 cardinals and 1 ram would make for a good stocking.