Q: None of us can agree what the tailing fish might be in this photo, taken off Southern California - a broadbill, a striped marlin or a blue marlin. The problems: The tail is very tall, and there seems to be a small second dorsal fin about halfway between the first dorsal fin and the tail, which would rule out any of the billfishes. One theory is that the middle fin is a remora, but a remora doesn't really look like that either. So what is it? - Jeremy Johnson, Sacramento, California A: A large pelagic fish like this off Southern California would almost have to be either a billfish or a giant bluefin tuna. It can't be a broadbill swordfish because that species has no large second dorsal fin. However, a marlin's second dorsal fin should be farther back, much nearer the tail than the dorsal fin. In this fish, the central position of the second dorsal fin is closer to that found in tunas, but the fins aren't the right size or shape for a tuna either. Mike Leech, president of the International Game Fish Association, suggests that this might be a deformed billfish - one that is unusually short for its weight and girth. Short, stubby billfish are uncommon, but not unheard of. The IGFA has a photo of one such sailfish that's about half as long as it should be for its girth and the size of its head and fins. In another case, I once saw a blue marlin on the docks at Bimini that was so short and round it was proportioned more like a tuna than a billfish. It's possible that this fish also could be a marlin with an unusual body shape.