Fish weight

[Tenko]

Hi

I've been trawling the net (no pun intended) for ages trying to find an aquarium fish weight calculator.

I've found a few sites that cover fish such as salmons, carp etc, and provide formulas like

(girth * girth * size) / 800
or
4.83 + 1.923 * Log(length) + 1.157 * Log(girth)

As a last resort I'll have to use these.

Ideally I'd like to find a source of information which contains the estimated sizes of adult fish of different species, but it seems a little hard to come by.

Can anyone suggest anything?

Thanks

 

[OohFeeshy]

What fish are you talking about

 

[JamesTasker]

How about weighing them

 

[OohFeeshy]

I was thinking more, put bowl of tank water on scaled, meaure weight, reset to 0 is poss then add fish and see what the weight is...

 

[JamesTasker]

Exactly, but you would need a damn accurate balance if you're weighing small fishes.

 

[bigben]

calculate the volume of the fish by estimating the size and then multiply by the density of water. this should give you a rough number considering fish are made mostly of water.

 

[JamesTasker]

It would be a very rough number.

 

[Paul_MTS]

Never really thought of going by weight on aquaruim/pond fish i always go by length.

i think the fish in a container is the best option, any calculation will be very rough made on assumptions.

by the way where abouts are you in essex??

 

[Bignose]

A kitchen scale would be accurate to a gram or so, if you want to do the container of water idea. If you use a well-marked measuring cup, you could see how much displacement a fish causes, giving you the volume, then muitply by 1000 kg/m^3 (the density of water).

John J. Videler's book Fish Swimming shows how the average swimming speed of fish is related to their mass, and uses data from several papers. One of those cited papersmight tell you how the researchers measured the mass of thier fish.

 

[Tenko]

Thanks for all the suggestions.

I would like to find the weights of a variety of fish, but at the moment I'm after Cardinal, Neon and Rosy Tetra, Angelfish and Bristlenose Catfish. As Tetras are so small, anything other than slapping them on very accurate scales wouldn't produce very reliable data.

I hoped that there might be some source of information which already had this information, I expect someone somewhere has weighed tropical fish at some time or other. I can't find it though.

I've read a few sources which suggest feeding fish 1% of their body weight per day (this isn't why I need to know their weights, it's for a uni project), but I'm surprised that the same sources don't suggest reliable ways of estimating fish weights. Basically, I have approximate oxygen consumption for various weights of fish, but no way to estimate fish weights.

Bignose, I've had a search for that book. I can't find it stocked in any local library, but it's on Amazon for £138! Must be a hell of a book. I've emailed the author to see if he could provide me with any sources, worth a try.

paul_v_biker, I'm from Colchester, bit of a hole if you ask me, an expensive hole. I've been to Kirby a few times to play cricket, friendly bunch of guys over there.