I recently purchased a twenty gallon long aquarium and intend on setting it up in a week once I get home from vacation. My plan as of now is to transfer over the livestock of my ten gallon since this is really more of an upgrade. This consists of my beta fish and some ember tetras. I also have some cambodia, a few small swords, and some other plants. I know for sure I will be filling my school of embers out to about 7-8 individuals and was also hoping to get another school of some smaller fish. I can't decide what to get or how well it would work with my current stock though. I am currently thinking about either CPDs or ottos.
The beta fish, named spot, is pretty good with the tetras but gets fairly nippy when he firsts sees a new thing and has eaten shrimp and I have seen him try to eat smaller snails. I was wondering if I should avoid micro fish or fish like ottos that spend a good amount of time stationary.
My water has a PH around 8 and is hard. I also am using eco-complete, not sand, if that affects my options for bottom dwellers. I am very open to options as well as numbers. If I did do the CPDs I was wondering if twelve would be to many or if I would be overstocked. I wouldn't consider it to be heavily planted but there should definitely be a good amount of green once i finish.
As far as equipment goes I was going to use a fluval C2 from my 10 as well as a 50 watt heater that says it is good for up to 20 gallons.
Thanks in advance for the help, any and all suggestions are appreciated.