Spoiler forLet it inside a plastic bag, tie a string on the opening (let no air),
fish in the bag of water is heavier than the bag of water without the fish.
Tie the end of string to a weigh hook with the fish bag fully submerged.
Spoiler for CommentsI've been pondering this one... and I am not sure if it would work without lifting the bag out of the aquarium (at least if I am picturing it correctly). If the bag (with or without the fish) is submerged in the aquarium, then a weight hook would be useful for measuring its buoyancy, but not its weight. A bag full of water, submerged in water, would have virtually zero apparent weight (the plastic of the bag and the material of the string would contribute a little, technically); if the fish had his air bladder balanced right, the bag with the fish inside would also have virtually zero apparent weight, at least while underwater. (In fact, if the fish had an overinflated air bladder, the bag with fish inside might appear to have negative weight while submerged, as the fish would tend to float and push the bag to the surface.)
Yes, that is right.. the bag of water with fish inside will sink (give submerge weight ) but this is not the "out of the water weight" . Also i agree, a bloat fish makes the bag less dense than water ,good physics thanks.
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Guest Message by DevFuse
How can you weigh a living fish?
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