How to keep red swordtail fish well?

Red swordtails adapt to slightly acidic or alkaline water and tolerate cold fairly well, living in 20-26 C, but keep temperature and water quality stable to avoid stress that lowers immunity and invites disease. They like to jump when scared, so cover the tank.

Provide enough oxygen; without an air pump, change water often, but only 1/3 to 1/2 each time so the fish can adjust.