'Somebody' is wrong in that the original 'Hush Puppy' (shoes) was indeed a Basset (with a shocking front!!). https://en.wikipedia.org/wiki/Hush_Puppies
(photo top right).
Further I see no Cocker Spaniel in him although there are a number of breeders (in the UK?) who are producing a Basset-Cocker mix, SADLY. To be honest, I see more Basset-Dachshund in your dog although it's interesting to me, that when the Basset is involved in mix-breeding, the result tends to almost always favour the Basset (especially ear and back length and lowness to the ground!). So it could be there's something like Labrador in that dog (otter-like tail and colour).
As for what food, that would depend on where you are and what he's been eating up to now. If you switch without doing it gradually, over at least a week of mixing the new with the old, you will upset his digestive system. I'd certainly avoid anything that's cereal-based, picking something that lists meat, or fish, as the first ingredient. And avoid anything that's high in protein. The Basset is a breed prone to GDV (Bloat with torsion) so you'd do best to feed two smaller meals a day, and not to feed after exercise immdiately, or exercise for about 2 hours after eating.
ps I have to say I have seen far worse fronts on a purebred Basset!!! Nice. Keep his nails clipped back.