everyone read! VERY useful info!!!

Discussion in 'Flathead Catfish' started by brandonbtbt, Jul 6, 2009.

  1. brandonbtbt

    brandonbtbt New Member

    Messages:
    99
    State:
    Cambridge, OH
    hey everyone... so today my buddy told me he caught a 35 in flattie that weighed 30 pounds... i told him NO WAY, he's lying, etc etc...
    so, during lunch break i got to thinking... how about i graph all my flatheads caught by length vs. weight (digital scales only) and see how much he's lying....

    so what i did was plot 7 different weights and lengths in excel, graphed them and added a trendline with a formula... (a trendline is basically the AVERAGE line the plots make)... i have my graph to where you can take the formula, plug in the length of your flattie and out pops a good guess of the weight... (it also works in reverse order too)... of course you can always measure the fish and follow the graph with your finger to get a good guess as well...

    i figured this would be GREAT for people that don't have digital scales or have an unreliable spring scale..... everyone has a tape measure and that will be all you need!

    of course the graph is not perfect and the more data points i have the more accurate the trendline will be...

    so, i'm asking everyone to post the weight (DIGITAL ONLY PLEASE!!) and length of their flatheads caught... i will take all the data posted, add it to my graph and make the equation more accurate so all you have to do is know how long the fish is to get a good estimate of the fish's weight... (NO MORE BIG FISH LIES!!!!!)

    i have added a sample of the graph and what i'm trying to do... hopefully everyone can understand it fairly well and and will be able to catch people in them infamous HUGE fish tales...

    i'm also going to post this in other threads and maybe if it works well enough i could publish this kind of research!!!!

    thanks everyone!!! maybe after i get about 50 more data points we can all have an easier way to get a more accurate estimate of a fish's weight and/or length!!!!!!!
     

    Attached Files:

  2. Hoopie

    Hoopie New Member

    Messages:
    818
    State:
    Ohio
    MY son caught a 35.5 in last night that wieghed in at 18.3. Female full of eggs.
     

  3. brandonbtbt

    brandonbtbt New Member

    Messages:
    99
    State:
    Cambridge, OH
    hey everyone... so today my buddy told me he caught a 35 in flattie that weighed 30 pounds... i told him NO WAY, he's lying, etc etc...
    so, during lunch break i got to thinking... how about i graph all my flatheads caught by length vs. weight (digital scales only) and see how much he's lying....

    so what i did was plot 7 different weights and lengths in excel, graphed them and added a trendline with a formula... (a trendline is basically the AVERAGE line the plots make)... i have my graph to where you can take the formula, plug in the length of your flattie and out pops a good guess of the weight... (it also works in reverse order too)... of course you can always measure the fish and follow the graph with your finger to get a good guess as well...

    i figured this would be GREAT for people that don't have digital scales or have an unreliable spring scale..... everyone has a tape measure and that will be all you need!

    of course the graph is not perfect and the more data points i have the more accurate the trendline will be...

    so, i'm asking everyone to post the weight (DIGITAL ONLY PLEASE!!) and length of their flatheads caught... i will take all the data posted, add it to my graph and make the equation more accurate so all you have to do is know how long the fish is to get a good estimate of the fish's weight... (NO MORE BIG FISH LIES!!!!!)

    i have added a sample of the graph and what i'm trying to do... hopefully everyone can understand it fairly well and and will be able to catch people in them infamous HUGE fish tales...

    i'm also going to post this in other threads and maybe if it works well enough i could publish this kind of research!!!!

    thanks everyone!!! maybe after i get about 50 more data points we can all have an easier way to get a more accurate estimate of a fish's weight and/or length!!!!!!!



    please go here to see original post

    http://www.catfish1.com/forums/showthread.php?t=116731
     
  4. lendog

    lendog New Member

    Messages:
    2,141
    State:
    berks, PA
    i think the girth also is a factor, last year i had one that was long 42 inch but skinny, only weighted 25.8#, and the 28# i had this year was also very long and skinny where as the 35# had a gut but was about the same length as the 28#
     
  5. Welder

    Welder New Member

    Messages:
    4,834
    State:
    Missouri
    Some flats are long and lean and look like a tadpole wile others are short compact and just massive in body girth and head. I would almost surmise from what I have seen over the years there are dif sub groups of flats in the MO and miss drainages, I have also seen alot of dif color patterns on em even from the mo. You also have to take into account male and female fish as the heads are dif sizes 90% of the time.
     
  6. recordbreakin1

    recordbreakin1 New Member

    Messages:
    746
    State:
    texas
    Thats interesting.
     
  7. HRCats

    HRCats New Member

    Messages:
    1,081
    State:
    Ohio
    Girth is very much a factor that is often overlooked. I caught a 38" flattie two years ago that weighed 29 lbs.
     
  8. buckethead

    buckethead New Member

    Messages:
    469
    State:
    arkansas
    Hey Welder,

    very interesting, never thought about it, they might be like a Gar, there are a lot of different Gar, same with a Flat Head maybe, you know that the Flat heads that have the huge heads and small bodys or a different sub species than the ones buit like a snake, I have also seen some that look like a Brindle Bull Dog, just covered in spots.

    Good thread

    cliff
     
  9. lendog

    lendog New Member

    Messages:
    2,141
    State:
    berks, PA
  10. slimdaddy

    slimdaddy Well-Known Member

    Messages:
    2,600
    State:
    Nelsonville, Oh
    Name:
    Keith
    my pb was 56.5# and was 46.5'' long dont know what the girth was my other fish i just weighed and never put a tape on them so that dont help
     
  11. rasmotherman

    rasmotherman New Member

    Messages:
    1,043
    State:
    salineville, ohio
    lets not get all technical here. fish stories belong on the side of makebelieve. i think the more outrageous the story the better. you ever hear the one about the 60# flattie caught with a tree branch? thats legendary.
    * all statements made in this post are not up for debate:wink:
     
  12. Catmanblues

    Catmanblues New Member

    Messages:
    2,224
    State:
    S.E Ohio
    The graph may work somewhat but I tend to believe after alot of the spawning that is occuring now has finished it could throw off the measurements.
     
  13. Fishgeek

    Fishgeek Active Member

    Messages:
    1,149
    State:
    Indiana

    Brandon, great idea but you can save yourself a lot of work by simply getting ahold of you local OH DNR fisheries biologist...or maybe even looking on the DNR's website. Calculating length-weight relationships is a pretty standard practice in fisheries. I googled "fish length weight chart" & quickly found a site for Louisiana. according to their length-weight relationship a 35" FHC will weigh 21 pounds. 30 lbs sounds a bit large for a 35" flattie but it's certainly possible...especially if it was a big female packed full of eggs.

    As Welder said, there are differences between males & females but these charts are typically based on pretty large sample sizes so the they tend to be relatively good estimates of weight.

    I tried attaching the link but it doing something goofy in the post...just google "fish length weight chart"
     
  14. DTro

    DTro Active Member

    Messages:
    243
    State:
    Minnesota
  15. ShilohRed

    ShilohRed New Member

    Messages:
    4,339
    State:
    West Tn
    I've handled thousands of flat heads, and can tell you lots of the same fish in length will not weigh anywhere near the same weight. Some are fat (like me) others are slim and lean.
    If the fish he caught was full of eggs then that makes most formulas be way off.
    If say a 40" flat head has eaten a 5 lb meal then that will also make it be off.
    I hope you can get lots of info on this, and make it where people can get close to what they think it weights. But also this was done on here a few years ago also not sure what happed to it. But there was a guy that had the same deal.
    Good luck with this.
    Pete
     
  16. DTro

    DTro Active Member

    Messages:
    243
    State:
    Minnesota
    I’ve been doing this for a few years now. Basically started collecting data from hundreds of fish that I and friends who I could trust, caught.

    From that data I came up with a formula L*L*G/1275.

    It’s a very accurate formula, at least for the fish in the Northern Region here and has a tolerance of +/-2lbs.

    Here’s a link to a thread I started a couple of years ago with a conversion chart that I made up based on that formula.
    http://www.catfish1.com/forums/showthread.php?t=48582&highlight=conversion

    Of course there are exceptions to the rule, but I know I can trust the formula and very rarely will weigh a fish under 50lbs anymore, and only then to do a spot check of the formula.
     
  17. Fishgeek

    Fishgeek Active Member

    Messages:
    1,149
    State:
    Indiana
    Pete,

    I don't think anyone is saying that every fish the same length is going to weigh the same. These length-weight estimates can be useful if you don't have a scale or don't want to weigh your fish...our as Brandon said, what's to check on someone's fish story. The L-W relationships will give you a pretty good estimate of weight...a ball park figure. As someone mentioned in DTro's original thread about his conversion chart, These can be very functional if you don't want to stress the fish anymore than necessary.
     
  18. adamj

    adamj New Member

    Messages:
    286
    State:
    buckeye land
    Very good idea Brandon. I'm not crazy about any formula but compiling a database of many fish would give a very general idea. Of course all of the lengths and weights would have to be accurate and the more fish the better for the trendline. Here are some that I have weighed and measured. 40lbs/43.5by28.5, 37lbs/44by26, 33lbs/39by26, 26lbs/36by25.5. pm me if you want more.
     
  19. rushing

    rushing New Member

    Messages:
    561
    State:
    Minnesota
    The (Length x Length x Girth / 1275) is prety darn accurate method of calculating weight for a flattie.
     
  20. brandonbtbt

    brandonbtbt New Member

    Messages:
    99
    State:
    Cambridge, OH

    what significance is the 1275?