How a Dart frog would adapt

Dart Frogs are known for their poison, they also live in rainforests, however, what if the rainforests were flooded and made into Freshwater habitats? Since Dart Frogs don’t really need lungs underwater, they’ll have to lose their lungs sadly. Their good sight would be replaced by speed to eat more food quicker. Using their tongue they can poison prey to eat them. Their teeth are mostly on their top jaw. they would have to move their teeth down which is more effective for chewing. They would become omnivores due to the abundance of plants and fish. They use their back legs and tail to swim underwater. Their long and poisonous tongue could grab prey and eat them. Due to their purple and blue color scheme, they could camouflage into the color of the water and hide in rocks to catch their food.