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The retinal projection to the ipsilateral optic tectum was examined first in normal channel catfish. After unilateral optic nerve section and horseradish peroxidase (HRP) application, a sparse retinal projection was seen in the ipsilateral optic tectum. When HRP was applied to the ipsilateral rostral tectum, labeled ganglion cells were observed in the ventrotemporal quadrant of the ipsilateral eye. Electrophysiological mapping of the ipsilateral projection confirmed that cells in the temporal retina projected to the rostral tectum. When albino catfish were examined using these techniques, the ipsilateral retinotectal projection was found to be much sparser than the ipsilateral projection of normal catfish.

Catfish and goldfish received small, unilateral tectal injections of horseradish peroxidase. In these fish a population of large diameter tectal efferent axons could be seen travelling to the hindbrain. Each of these axons gave up to 19 collateral branches. These branches arborized in or near the dendritic fields of the ipsilateral nucleus lobobulbaris and oculomotor nucleus, and the contralateral trigeminal nucleus, oculomotor nucleus, abducens nucleus, nucleus lateralis valvulae and medial reticular formation. The results suggest that these axons are involved in triggering eye movements.