hi there, have you ever noticed how damned fast little fry are? im doing an experiment to try to calculate how fast they dart around in miles per hour. how would i go about doing this experiment? put a ruler on the tank and slap the side?
help me with a term paper?
- Thread starter Hans
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Step up to the metric system dude! The only right way to report this is metres per second (m/s).
As for how you could do it, now that's tricky... Problem is getting them to go straight. You could set up a couple of optical sensors, like the kind on automatic doors, to trigger a timer to start and stop. If they were a fixed distance away, you'd have speed.
However, this is only good if they go straight, if they go in diagonal, you're scuttled.
Maybe this can help:
Determining fish size and swimming speed in cages and tanks using simple video techniques
Petrell RJ, Shi X, Ward RK, Naiberg A, Savage CR
AQUACULTURAL ENGINEERING
16 (1-2): 63-84 MAR 1997
If you can get ahold of that at a local University library...
As for how you could do it, now that's tricky... Problem is getting them to go straight. You could set up a couple of optical sensors, like the kind on automatic doors, to trigger a timer to start and stop. If they were a fixed distance away, you'd have speed.
However, this is only good if they go straight, if they go in diagonal, you're scuttled.
Maybe this can help:
Determining fish size and swimming speed in cages and tanks using simple video techniques
Petrell RJ, Shi X, Ward RK, Naiberg A, Savage CR
AQUACULTURAL ENGINEERING
16 (1-2): 63-84 MAR 1997
If you can get ahold of that at a local University library...
I would think a ruler and a stop-watch would work...the only problem is getting the fry to swim a straight line in front of the ruler, and then being fast enough on the stop watch, then doing the math. I think ultimately a camera would be needed. Something you could play back in slo-mo. But you have to know how many frames per second, then count the frames per inch and work out the math that way. I've never attempted anything like that, so I really don't know. Just throwing out idea's.
dont know if this would be cruel in todays world O_O, but u could set up some long container with variable flow rates of water from one end to the other.
90% of fish will swim against the current, so increase it to the point where they cant swim against it anymore, then u would get some idea of a max spd
90% of fish will swim against the current, so increase it to the point where they cant swim against it anymore, then u would get some idea of a max spd
Except then you have to start worrying about hydrodynamics. I suspect that fry are small enough to be close to the boundary between turbulent and laminar flows. Not sure though, haven't checked.
Besides, one's ability to move against a particular force isn't necessarily indicative of potential speed.
It's a tough question, I think that it comes down to camera work.
Besides, one's ability to move against a particular force isn't necessarily indicative of potential speed.
It's a tough question, I think that it comes down to camera work.
If you are dealing with REALLY small fry, you might have a device set up where there was only one direction they COULD swim... such as a box where the only way out was through a straw of a fixed length. Measure the time it takes them to go from one side of the straw to the other.... don't know how practical it would be though. But a lot like a maze in concept, just forcing them to go a certain way rather than giving them an option of going 2 ways.
EDIT: I R 1 GUD SPEELER
EDIT: I R 1 GUD SPEELER
bait them with something. thread through a shrimp pellet or cube of frozen bloodworms or such. get the fish' attention and run in from one end of the tank to the other. theoretically the fish will follow it. get someone to help you and taping it would be a good idea. move the bait as fast as possible (maybe putting it on a stiff wire is a better option here than thread) and time it from when the fish goes from one end to the other. You know the measurement of the tank, you know the time of the "run." you should be able to extrapolate from that.
I think.
I think.
Not only is it a problem to get them to go straight, but you will probably have trouble getting them to swim the desired path without pausing, etc. As a rule, animals will do whatever they dern well please in any given experiment.
Anyway, slapping the tank is probably the best way to get them to move as fast as possible in any given direction...
Baiting them probably won't work as reliably as scaring the bejeezus out of them.
Anyway, slapping the tank is probably the best way to get them to move as fast as possible in any given direction...
Baiting them probably won't work as reliably as scaring the bejeezus out of them.
Ah, good. I was having trouble with that, but I just assumed it was due to my ineptitude in physics.
Depending on your university/college, they may have an A/V department. From there you might check out a camera. (and hopefully they have an editing room) Tape a ruler or measuring tape to the front glass. Start recording. Lure the fry to one of the front corners...presumably with food. Then slap the tank. Providing you have enough fry, hopefully at least one will dart directly across the front glass. And hopefully somewhere in the area of the ruler. May take several attempts to capture one moving across the front glass. Then head back to the editing room and play it back frame by frame. They should know, or be able to find out the frames per second of their camera's. With some luck, they may even have a high speed camera. I'm thinking this is the only way to get anywhere near an accurate mph. Then you'd need to know how many inches are in a mile and how many seconds are in an hour. blah blah blah
Another thought...you could check with your local police department, explain to them that you're doing a paper for school and need to "borrow" one of those nifty radar gun thingies. I don't know that they can track something so small, but might be worth checking into. (please don't laugh...it's just an idea)
Another thought...you could check with your local police department, explain to them that you're doing a paper for school and need to "borrow" one of those nifty radar gun thingies. I don't know that they can track something so small, but might be worth checking into. (please don't laugh...it's just an idea)
