A new lawsuit suggests the ever-popular Subway tuna sandwich doesn't include ... tuna.

Karen Dhanowa and Nilima Amin are suing the chain because the mayonnaise covered protein between the buns of their subs was not only not tuna but that it wasn't even fish.

"Independent testing has repeatedly affirmed, the products are made from anything but tuna,” reads the suit. “The filling in the products has no scintilla of tuna at all" and is "made from a mixture of various concoctions that do not constitute tuna, yet have been blended together by defendants to imitate the appearance of tuna."

Subway denies the allegations.

“There simply is no truth to the allegations in the complaint that was filed in California,” the spokesperson said in a statement. “Subway delivers 100% cooked tuna to its restaurants, which is mixed with mayonnaise and used in freshly made sandwiches, wraps and salads that are served to and enjoyed by our guests.”

Dhanowa and Amin are seeking damages and want to roll their lawsuit into a class action, which would allow anyone who ever paid for a Subway tuna sub to get in on it.

This seems a pretty straight forward case, so we should soon get to the bottom of whether Subway tuna is tuna.

What would you bet?