Deactivated Fish?
February 19, 2005 12:40 PM   Subscribe

What sort of effect, if any, do department and pet store security scanners have on live aquarium life? I'm referring to the scanners at the entrances/exits of the store that go off when you buy something that isn't properly deactivated at the register.

I work in a Wal*Mart and there seems to be two different beliefs among the cashiers. Most of them believe that the door scanners do something to the live fish and snails that results in them dying shortly after leaving the store, the most frequently cited effect being that the scanners somehow electrocute or "scramble" the fish. These cashiers tell customers to hold the fish over their heads in order to keep them out of the scanners' reach.

The rest of the cashiers believe that if the larger pet stores don't warn people about this potential danger, there's no reason to worry about the scanners somehow killing the fish; however, based on experiences with giant pet stores, it is entirely possible that the cashiers don't know about these dangers, or simply don't care.
posted by chickygrrl to Pets & Animals (9 answers total)
Well, they're just magnets, so I doubt they do anything. I wouldn't really trust Wal Mart employees to understand the effects of magnets on aquatic life, anyway.
posted by borkingchikapa at 12:55 PM on February 19, 2005

Wal-mart apparently uses the Sensormatic Ultramax system. This has a great big electromagnetic in the "scanner" that switches on and off at a high frequency. The tag is tuned to that frequency and vibrates at it. The electromagnetic is turned off completely for a short period every so often, and any tag in range will keep vibrating for a short period, which is picked up by a sensor in the post, setting off the alarm. There's no "scanning" going on.

So the question is are electromagnetics harmful to fish? I don't know, but probably not.
posted by cillit bang at 1:01 PM on February 19, 2005

I've never heard of inventory control tags affecting fish. I would guess that the problem stems from the fish being put in tanks that are not properly cycled, or the fish not being properly acclimated into their new home (sudden shifts in water chemistry can send fish into shock.) Fish should not be added to a tank the same day the tank is set up- so if customers are buying both tanks and fish the same day, that's your answer.

Also, I know that some Wal-Marts have very good fish departments, but not all of them do, and the fish could possibly be weakened and stressed from their stay in the store.
posted by ambrosia at 1:04 PM on February 19, 2005

I've bought the same (type of) fish from a Walmart store and a major pet store, as have my friends (we all have sort of a betta fish fetish), and the ones we've bought from Walmart have been uniformly more sluggish and have had dramatically shorter lives than the ones bought from a chain pet store. In all cases, we have not held the fish over our heads as we walked through the scanner, so I doubt that's the reason why.
posted by muddgirl at 1:05 PM on February 19, 2005

A quick bit of googling says there's only two possible ways the fish could be harmed by EM radiation. Either it's high enough frequency to break the chemical bonds in the fish (like X-rays can). It's not anything like, so rule that out. The other option is that it causes a heating effect in the fish (like microwaves can). Again, it's nothing like in the right range. Your cashier friends are crazy.
posted by cillit bang at 1:18 PM on February 19, 2005

I wanted to take pictures of interesting dead fish. Actually I wanted to scan them on a flatbed, which would entail killing them, so I opted for post-mortem specimens. I went to the pet store and scooped all the dead fish from the tanks.

Small inexpensive creatures like fish and snails are actually sometimes purchased as food for other animals, so I expect the health inspections are fairly perfunctory. Walmart=baitshop?
posted by Jack Karaoke at 2:42 PM on February 19, 2005

I am absolutely sure you cannot damage marine life with any retail theft detector.

As mentioned above, the cause of the fish dying is probably improper aquarium setup/water conditioning.
posted by azazello at 4:29 PM on February 19, 2005

Have you ever looked in the tanks at Wal-Mart in comparison to other stores? They're in terrible condition. Half the fish are dead or on their way out, and the tanks are filthy. Wal-Mart does not care for their fish properly, leading me to believe that is why they die quickly. I am a regular shopper, but I refuse to buy their fish.
posted by chiababe at 5:29 PM on February 19, 2005

I second chibabe's comments. Every time I look at the conditions of the fish in the tanks at Wal-Mart I shudder. I know that some stores are probably better than others, but I tend to warn people off buying live stuff from there. Aquarium and other pet supplies however are great as the prices are generally lower than at dedicated pet stores.

Care of the fish while in the store and once into their new homes determines wether the poor critters live or die, not the EM devices at the doors.
posted by aedra at 11:42 AM on February 20, 2005

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