Fish Heads, how much would a 18.5 inch Smallmouth Bass weigh?

[22Fathoms]

I really need to know.  Thanks for the answers.

[AnglingArtisan]

probably around 4 lbs. or so

[Perca]

A commonly used formula for determining the weight of bass is; girth x girth x length divided by 800. You only gave the length, and as we all know, fish can be slim or pot bellied...eh? If you can get the girth, plug the numbers into the formula and see what you get.

[AnglingArtisan]

My reply was like an average of similar length smallies from reproduction suppliers.
Just a rough estimate 

[JL]

Smallmouth are not as thick as a largemouth being more streamlined and you need to factor in some things if you really want to be accurate. Was full of eggs as in prespawn? Did it just feed, etc.?An educated guess would be around 4 pounds here in New England, while a more Southern bass would weigh a little more, but not over 5 pounds.

[Marc]

The avg. 18.5 smallie here in WI. is slightly less than 4 lbs.

[John C]

JL, I have to disagree with your generality. I see many broadback, smallies out if the highland resiv. lakes aroound me.

The younger fish  tend to be the slim fish here, but as the smallmouth ages in these lakes, they become very broadbacked, this starts happening in about the 4th or 5th year here. While scuba diving I see many smallies over five pounds.

Up to about the  4th or 5th years the smallies do tend to be thinner as You said.

[Cecil]

Here the smallmouth are a denser fish then largemouths of the same length. From Lake Erie an 18.5 fish can easily weigh 4 lbs. while an 18.5 inch largemouth will only weigh in the 3 lb. range. I do remember catching an 18 inch smally in Webster Lake of Massachusetts that was only 3 lbs. Maybe regional differences? 

[Cole]

Region plays a major role. I'm in NW Mo and any smallies around here 18.5" long will go just over 3lbs. but I've caught fish in NW Ontario that length that were nearly 5 lbs! Absolute footballs. As John C said, the younger fish are more streamlined which may be the reason for the girth differences in the 2 regions, as the Ontario fish are probably at least 10 years older than the same length fish in MO or KS (where most of mine come from).

[Cecil]

There is a river near me where they are almost as skinny as trout. It's probably due to tapeworms which are common in smallmouth in some waters.

[GBRUCH]

Here along the susquehanna river in PA the river bass that length are pushing 3 1/2 ponds.  In Ny lake Erie fish that size in may(pre-spawn) are pushing 4 1/2 ponds on average.  Love those Lake Erie footballs.

[Jims Wildlife Studio]

In Lake Ontario at the end of August when fish are schooled up, this size will also vary from 3 1/2 to 5 1/2 lb's. My son actually won the Outdoor Life Fishing contest a few year's ago with a 5 3/4 lb smallmouth 19 " for his age division at the time was 9.

[Mark V.]

I would have to agree with the other Marc and GBruch. I think 3-3 1/2 pounds for a 18.5 being that a Largemouth would weigh maybe 4.5 pounds depending on girth. I Have a 19 inch that I caught and it weighed 3 pounds 6 Oz. on a certified scale and it has a pretty good sized belly. This was a MN. fish. Maybe would weigh a little more from down south. I do alot of smallmouths and a 4-5 pounder is 20-22 inches. Just my thoughts though,Mark V.