subs. phr. (old naval).A ropes-end; TO HAVE SALT-EEL FOR SUPPER = to be thrashed (B. E., GROSE).
1695. CONGREVE, Love for Love, iii. 7. Ben. But an he comes near me, may-hap I may have givn A SALT EEL FORS SUPPER for all that.
1752. SMOLLETT, Peregrine Pickle, xl. If so be as how you have a mind to give him a SALT-EEL FOR SUPPER.