Aquatic frogs are nocturnal, meaning they are most active at night. This means for the majority of the day they are going to want to go somewhere dark. Hence the hiding spot.
Frogs swim to the bottom of the tank quickly after they’ve surfaced for air. Therefore if you have gravel, or even worse, pebbles, then this could damage the frog’s head.
Unlike fish, frogs have limbs that can get trapped in a grated filter.
A good rule is about one quarter or one half of a bloodworm cube per frog. This may vary according to their size.
You should be feeding your frogs every two to three days. They are scavengers so it is how there body works and it is natural.