[MSG]

Not sure what kind of fish you have, but I hope your bowl is made out of GLASS.

Plastic/acrylic tanks can melt with this method.

A visual of what I'm talking about.

• Find a desk lamp that uses the standard incandescent bulbs. Lower the amount of water in the fish tank to about 1-2 gallons and place the light as close to the bowl as possible.
  
• Also tie/wrap your fish bowl with a sweatshirt/sweater/scarf to give it some insulation.
  
• Incandescent bulbs are better at creating HEAT than light.
  
• Make sure you use incandescent bulbs instead of CFLs & NOT halogen bulbs.

I have a OTT Lite desk lamp that uses a 4 bar 26W CFL tube, once it's on for over 30 minutes the surface of the light gets to about 110-115 degrees.

• A standard 25W incandescent should run hotter than the CFL. I'm going to guess 130-140 degrees.
  
• 40W-60W will definitely work too but be very careful with splashing water on the bulb when it's on. Use a lid/clear glass plate on the bowl if possible.
  
• Definitely check water temp every 30-60 minutes to make sure the temperature is where you need it to be.

Good luck

 

[MSG]

Well, it's only a 25W light bulb. I would leave the lamp ON all through the night.

Compared to a space heater that uses 700W or a 1500W. 25W is NOTHING. It's worth wasting a incandescent bulb if it keeps the water warm enough to keep the fish alive.

Certain types of betta fish are hard to replace.

• Most basic desktop computers use well over 100W of electricity.
• 27" + LCD TVs usually use well over 150W.
  
• 25W incandescent bulbs are pretty much useless now with CFL's going for less than $0.50/each.
  
• When I suggested the light bulb as a heating source, I meant leaving it ON as long as necessary.

Geo, your suggestion is good one though.

Leaving your fish with someone who lives in a well insulated stuffy concrete apartment building will work too.

• A heating pad usually doesn't get THAT hot. 130 degrees MAX for a h-pad but it depends on how cheap the plastic tank is. I've seen the top of 20G-30G acrylic tanks get warped from a high wattage light fixture mounted too close.
  
• Most small plastic fish tanks under $30 are REALLY easy to melt.

 

[MSG]

You can use the desk lamp to heat the glass bowl from the BOTTOM then.

Either way you can use the light to generate heat temporarily. Just have to be craftier about it.

If the fish is going to FREEZE anyway, why not try?

Also if you have a NICE cave/coffee mug, the fish might ACTUALLY use it for shelter now to escape the light.