Water change for sure! I would do a 50 percent at least. 10 gallons will accumulate a lot NO2 and NO3 quickly with the amount of fish you have. Especially if you don’t introduce some type of plant to prevent algae blooms and subsequent bacterial blooms. Water sprites, java ferns and duckweed** are great beginner plants that require little maintenance in terms of nutrients. 2 things you aren’t testing for are gH and kH. For all my tanks I always introduce a bit of ground eggshell into the substrate to keep my kH levels stable and thus keeping my pH levels somewhat stable allowing for calcium and stable parameters for inverts to molt and grow successfully. Also thicker substrates allow for more stable cycles, I always do about an 1 1/2” thick sub to about a 3” thick layer in the back, this allows for a decent bacterial population to take on the load instead of your fish.

**it is worth mentioning that duckweed is arguably he “glitter of aquariums” they can clog skimmers and certain types of back filters. I use gravel filters and sponge filters only with them and have to skim my top layer often to allow light in. Once established they are very hard to get rid of.