Catfish
Flathead catfish
Pylodictis olivaris. Also called shovelhead.
Length to weight chart, typical size by age, and how to photograph a flathead catfish so fishline measures it well.
- Typical top length
- 50 in
- about 66.2 lb
- A 38 inch fish
- 27.5 lb
- 27 lb 8 oz
- Age at 38 inches
- about 12 years
- rough, varies by water
- Growth levels off
- about age 22
- gains slow to a crawl after
Flathead catfish length to weight chart
Estimated weight for a flathead catfish in average shape at each length, from the formula W = L^3.2 / 4,130 (W in pounds, L in inches). It is the same relationship fishline uses when it measures a flathead catfish from a photo.
| Length | Weight | Rough age |
|---|---|---|
| 18 in | 2.5 lb | 3 to 4 years |
| 20 in | 3.5 lb | 4 to 5 years |
| 22 in | 4.8 lb | 4 to 5 years |
| 24 in | 6.3 lb | 5 to 6 years |
| 26 in | 8.2 lb | about 6 years |
| 28 in | 10.4 lb | 6 to 7 years |
| 30 in | 12.9 lb | 7 to 8 years |
| 32 in | 15.9 lb | 8 to 9 years |
| 34 in | 19.3 lb | 9 to 10 years |
| 36 in | 23.1 lb | 10 to 11 years |
| 38 in | 27.5 lb | about 12 years |
| 40 in | 32.4 lb | 13 to 14 years |
| 42 in | 37.9 lb | 15 to 16 years |
| 44 in | 44.0 lb | 17 to 18 years |
| 46 in | 50.7 lb | about 21 years |
| 48 in | 58.1 lb | 22+ years |
| 50 in | 66.2 lb | 22+ years |
| 52 in | 75.0 lb | 22+ years |
Total length, nose to the tip of the pinched tail. Weights are for a flathead catfish in average shape. A fat fish, like a female before the spawn, weighs more and a thin one less, which a girth measurement picks up. Rows past 50 inches are bigger than typical for the species.
Size by age
fishline's growth model puts a typical flathead catfish at around 50 inches when fully grown, with most of its growth done by about age 22. Younger fish add length fast; older fish mostly add weight.
Age from length is rough. Fish in warm water with plenty to eat grow faster than this, and fish in cold or crowded water grow slower. For a quick estimate from any length, use the fish age calculator.
| Age | Length | Weight |
|---|---|---|
| 1 year | 5.7 in | 0.06 lb |
| 2 years | 10.7 in | 0.47 lb |
| 3 years | 15.1 in | 1.4 lb |
| 4 years | 19.1 in | 3.0 lb |
| 5 years | 22.6 in | 5.2 lb |
| 6 years | 25.7 in | 7.8 lb |
| 8 years | 30.9 in | 14.1 lb |
| 10 years | 34.9 in | 21.0 lb |
| 12 years | 38.2 in | 27.9 lb |
| 15 years | 41.7 in | 37.1 lb |
| 20 years | 45.5 in | 48.8 lb |
From a von Bertalanffy growth curve. Fish in warm, food-rich water grow faster than this and fish in cold or crowded water grow slower, so treat every row as a rough middle.
Weigh your flathead catfish
Enter the length, and the girth if you taped it, for an estimate on your fish.
Photo tips for flathead catfish
fishline reads length from the photo using whatever is in frame for scale, so a clean, side-on shot gives the tightest number.
- 1Big cats are heavy and slick. Hold them level with one hand under the head and one under the belly, side-on, rather than hanging them from the lip.
- 2Lay a big catfish next to something of known size, like a cooler, a 5-gallon bucket or a measuring sticker, and shoot straight down from above.
- 3Catfish carry sharp spines in the dorsal and pectoral fins. Get your grip set before you pose so you are not fumbling while the camera waits.
More catfish
Or skip the tape. Snap a photo and fishline measures it.
Species, length and weight from one photo. 5 free measurements every month.