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/sci/ - Science & Math

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5047321 No.5047321 [Reply] [Original]

Hey /sci/, I need some help

I have a friend that's doing internship in an aquarium/oceanarium and she needs to do some research for her final report.

It has been recommended that she relates the water parameters to the fishes appetite by weighting the fish. Since she cannot take the fish out of the aquarium, how can she measure weigth differences (or appetite differences)?

Also, feel free to sugest other research topics (if possible, related to aquaculture)

>> No.5047344

>>5047321
she can apporximate their size with spheres and then assume their density is 1kg/L

>> No.5047349

Weigh a tank of water, then put the fish in it and weigh it again.

>> No.5047355

Direct Determination is right out, no doubt for the health of the fish involved...
Observational Estimates are often inaccurate to the point of being totally useless...no good there
Volumetric Displacement would require the fish to be isolated from it's tank, so no go

I'd have to say Direct Comparison Against a Known Data Set is the way to go...then you need only the fishes length which is easy to do without bothering the poor thing by lining up a ruler on the glass or employing a camera.
Aquaculturists have long used this technique for commonly cultured species and data sets are abound.

i must note accuracy suffers when one attempts to estimate the mass of a typical aquarium fish, such as robust, gravid females, or ill specimens that are in an emaciated condition...due care will be needed

>> No.5047380

Why not use Archimedes' principle? Alternatively, >>5047349. I'm sure any facility that weighs fish routinely has a device you can use to weigh fish, such as a small aquarium on a scale or something.

>> No.5047381

>>5047380
>Archimedes' principle
because fish generally swim in water and therefore were intelligently designed to maintain neutral buoyancy

>> No.5047382 [DELETED] 

>>5047381

it would work for goldfish.

>> No.5047388

>>5047381
No, I mean, measuring the fluid that's displaced.

>> No.5047410

>>5047388
OP here, I'm pretty sure that the aquariums they got there are too big for the fluid displacement to be measured.

That might work to measure some small fish that are on quarentine (usually newborns), but she's not sure if they'll grant her authorization for that (she'll ask today what she can/can't do)

I'm not sure about the weight devices, but they don't usually take the fish out of the aquariums (it's not an aquaculture farm, it's just a huge aquarium).

>> No.5047424

ITT: EK knows her shit.

No one pays any attention.

>> No.5047428

>>5047388
If the fish floats, that means his overall density is exactly the same as the water surrounding him.