Some other points:
Dragonfish has 150 HP
while the normal fireball has a lot of endlag, the yellow version does not. because of this, if you keep dashing after using it, you can use your yellow fireball as a moving shield that destroys incoming projectiles and starts combos. it has a lot more startup though, so don't get too predictable.
Dash attack is invincible to all moving projectiles (so things such as dragonfish fireball, but not totem monster's bursted bubble) for a short while. If the opponent is using projectiles up close you can easily close the gap.
you can actually cancel your crouching attack into a yellow fireball attack (both variants of crouch attack can be cancelled, but the non-moving one won't combo). Simply do crouch attack without holding forward, then quickly do the yellow fireball input and press attack. This won't do that much extra damage but it will carry the opponent to the corner al lot quicker and it gives you more reaction time to plan your next move. with this technique you can do things like: air attack > crouch attack > yellow fireball > crouch attack > super. or if the opponent is cornered crouch attack > yellow fireball > crouch attack > yellow fireball > loop this until you get pushed too far, then end the combo with an up attack or super.
up attack beats out opponent's air attacks if you don't time it too late.
if you use up attack while dashing, you will keep some momentum. really important if you want to finish a combo with it.
You already sort of mentioned it, but crouch attack > super attack is an easy combo that makes dragonfish's crouch attack even more terrifying.