by TFH Magazine on January 5, 2011 at 1:30 pm
By Mike Hellweg
Necessity is the mother of invention, as the proverb goes. When I began using a large number of lasagna containers for newly hatched fry, I needed something to hold an airstone in place. They really don’t need filtration as I do an almost 100 percent water change every day, but still, insurance is a good thing and since I was using an airstone anyway, why not use a filter to hold the end down in the shallow water?
I couldn’t find a commercial design that would work in the very shallow trays, so I tried several homemade designs that others have used over the years, especially fellow killifish hobbyists since they use lots of small containers. After a few failed attempts I started looking at other things I had available in my fishy parts bin, which is full of all kinds of accumulated bits and pieces. I also started looking through my fishroom closet, which has shelves of accumulated filter parts, chemicals, and other things that I used at one point but no longer use. I keep these around, just in case.
I noticed that I had a large bag of sponge filter cores from my friend Ray “Kingfish” Lucas, which he gave me a few years ago. I used some of them, cut in half, to fill the overflows in my tanks to keep small fish from going down the drain. They fit perfectly in ¾-inch PVC fittings. That got me thinking…
I came up with a simple design made of ¾-inch PVC. It takes a tee, a 90° elbow, a U-bend piece of rigid airline tubing, and a small plastic airstone, along with two halves of the sponge filter core.
Drill a small hole in the outside bend of the elbow just big enough to tightly wedge the U-bend rigid tubing through it. I cut one end of the bend about halfway down, too, so that it doesn’t stick out of the elbow for better flow. I cut the soft plastic airstone in half, and insert it over the inner part of the U-bend tubing. The elbow then goes onto the center fitting of the tee, and the sponge filter cores go in either end.
Add a bit of fine gravel from an established tank to the inside of the tee, and there you have a perfectly weighted, seasoned tiny filter that will provide circulation and filtration in a 2-inch deep lasagna tray without causing any harm to the young fish.
The lasagna containers that I use are the disposable containers made by several large container manufacturers and sold in the kitchen gadget area of major retailers. They are approximately 10 x 13 x 2½ inches and hold about a gallon and a quarter or so. They have about the same surface area as a 5 gallon tank. They are lightweight, easily cleaned, and have snap on lids so they can be stacked, allowing you to keep a lot of fry in a small area.
They are easy to work with and easy to move, so I can stack them on a shelf in the fishroom all day, and simply move them to the counter next to the sink for water changes and fry feeding. They are perfect for hatching eggs and for newly free swimming fry. I put them on a shelf up high in the room as it is warmest there (around 78° to 80° most of the year) and the fry generally grow more quickly in warmer water. The small size keeps the fry close to their food so they can spend all of their energy in growing for that first crucial week to 10 days. After this, they are gently moved to 5 or 10 gallon tanks and converted over to brine shrimp and microworms.