The "dwarf-I" syndrome manifests itself by a slow down and finally an arrest of growth, by the obstruction of the gill chamber by food, a progressive anemia and by degeneration of the thymus, the intestine, the posterior limb buds and tail fins ; death occurs around the 25th day.

The "dwarf-II" syndrome appears on the 11th day ; gall bladder enlargement, lens and jaw muscles opacity, degeneration of the thymus, intestine and tail fins are its main characteristics ; the homozygous tadpole die from the 21st day on.

The "precocious oedema" phenotype is expressed ont the 5th day and is characterized by the presence of oedema in the eye and heart region and along the body, by heart hypertrophy, brain and pronephros abnormalities and by the folding back of the tissues of the lower jaw ; gill chamber and digestive apparatus are slowed down in their development and eventually degenerate ; death occurs form the 9th day on when the normal tadpoles have reached the feeding stage.