Perhaps the best response I could give is to quote from evolutionist
Arthur Strahler's anticreationist book, Science and Earth History -- The
Evolution/Creation Controversy (Buffalo: Prometheus Books, 1987), 408. This account is used by Duane Gish himself in Evolution: The Fossils Still Say No! (El Cajon, CA:
Institute for Creation Research, 1995), 79-80. Here is the exact quote from Strahler regarding the ancestors and transitional forms for fish evolution:
"Duane Gish finds from reading Alfred S. Romer's 1966 treatise, Vertebrate Paleontology, that mainstream paleontologists have found no fossil record of transitional chordates leading up to the appearance of the first class of fishes, the Agnatha, or of transitional forms between the primitive, jawless agnaths and the jaw-bearing class Placodermi, or of transition from the placoderms (which were poorly structured for swimming) to the class Chondrichthyes, or from those cartilaginous-skeleton sharklike fishes to the class Osteicthyes, or bony fishes [cites Gish's earlier book]. The evolution of these classes is shown in Figure 43.1. Neither, says Gish, is there any record of transitional forms leading to the rise of the lungfishes and the crossopterygians from the lobe-finned bony fishes, an evolutionary step that is supposed to have led to the rise of amphibians and ultimately to the conquest of the lands by air-breathing vertebrates.
"In a series of quotations from Romer (1966), Gish finds all the confessions he needs from the evolutionists that each of these classes appears suddenly and with no trace of ancestors. The absence of transitional fossils in the gaps between each group of fishes and its ancestor is repeated in standard treatises on vertebrate evolution. Even Chris McGowan's 1984 anticreationist
work, purporting to show 'why creationists are wrong,' makes no mention of Gish's four pages of text on the origin of the fish classes. Knowing that McGowan is an authority on vertebrate paleontology, keen on faulting the creationists at every opportunity, I must assume that I haven't missed anything important in this area. This is one count in the creationists' charge that can only evoke in unison from paleontologists a plea of nolo contendere."