From the 3 studies below it is unlikely that it was a Lepomis X Pomoxis cross, as the rate of fertilization , hatching and survival to 2 inches is very low ( but possible) in ideal conditions. Survival to a larger size is even more remote. These were in controlled conditions not taking into consideration natural crossing barriers like different breeding temps , times and methods of spawning and recognition of like kind. These lower the chances even more. My bet is it was a RES or a RES cross.

Intergeneric Hybridization of Centrarchids
JERRY L. WEST AND F. EUGENE HESTER

TEMPO OF HYBRID INVIABILITY IN CENTRARCHID FISHES
(TELEOSTEI: CENTRARCHIDAE)
DANIEL I. BOLNICK AND THOMAS J. NEAR

Phylogenetic Relationships of Sunfishes as
Demonstrated by Hybridization *
F. EUGZNE HESTER