Leopard frog do lay eggs early as soon as the water gets around 50F so that was a while back in TX and the tadpoles had time to grow to the size in the picture. Makes sense to me.
Off flavor experience is from putting tadpoles in an aquarium with some panfish. Panfish attempted to eat the tadpoles several times and then ignored them. I just assumed it was due to taste since it was obviously not texture. TNH you are welcome to try eating some of them raw after washing in salt water or lightly sauteed and we would welcome your official Pondmeister taste report.
