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Where to put the fry…

by TFH Magazine on November 30, 2009 at 2:15 pm

By Ted Judy

I am quickly discovering that the limiting factor controlling the number of species that will breed in my fish room this year is tank space.  More specifically, grow out space.  I can set up many species in 2.5 gallon tanks and get eggs within just a couple days.  The fry can stay in the small tanks for quite a while, but I need to move them if I want to use the tanks to spawn something else.  The growing fry get moved to larger tanks, usually 10-gallons, but sometimes into larger tanks where I can mix the babies of different (easily separable) species.  A few weeks ago I hit the wall on tank space.  No more grow out space to move fish into.  So I did what any average fish-addicted hobbyist would do… I built a new rack.

Like most fish room improvement projects the end product usually turns out to be a lot more expensive that what was originally planned.  My intention was to build a rack that would hold up to fifteen 3-5 gallon plastic ‘shoe box’ bins and five 10-gallon tanks.  What SHOULD have cost less than $100 to complete ended up closer to $800.  (Don’t tell my wife!)  Here is what happened…

The initial construction went as planned.  I built a 2×4 rack with dado joints so that the weight of the water is not held by the screws.  Making dado cuts without a radial arm saw is time consuming, but the rack is stronger.  I was able to knock the rack out in two afternoons at a total cost of less than $50.  So far, so good. 

Using dado joints may be time consuming, but it is stronger and will support the weight of an aquarium well.

Using dado joints may be time consuming, but it is stronger and will support the weight of an aquarium well.

I had enough tanks to put a row of 2.5-gallon and 5.5-gallon tanks on top (I had planned to put bins up there, but the glass was empty), and a few older 10-gallon tanks on the bottom row.  I started drilling ports in the air system to run filters in the new tanks and discovered that my 87 Watt linear piston air pump was not up to the job of servicing another two dozen air stones.  That pump is rated for 60 outlets.  Before starting the new rack I was already running 92.  So, in order to continue a new pump HAD to be purchased.  I bought the $435 120 Watt version.  Oh yeah!  Plenty of air now!  (Though the checkbook is a little deflated.)

A 120 watt air pump is used to aerate all of the new tanks.

A 120 watt air pump is used to aerate all of the new tanks.

The plastic bins cost $3 each, and I started with ten.  The size I bought hold about 3 gallons of water, but the surface area to volume ratio is excellent.  Surface area is where oxygen transfer occurs.  The greater the ratio, the better the bin or tank is for raising fry.  A 10-gallon tank has a 20 sq. in./gallon ratio.  My new bins have better than a 50 sq. in/gallon ratio!  That means that with my water change schedule (50% every 2-3 days) I can keep as many fry in a 3-gallon bin as I can in a 10-gallon tank.  Not bad for $3!

The large surface area to volume ratio in the plastic bins is great for fry since it promotes better oxygenation.

The large surface area to volume ratio in the plastic bins is great for fry since it promotes better oxygenation.

I planned to use some sponge filters I have laying around to filter the bins, but discovered that the filters are too tall.  I had to go out and purchase filters with a lower profile.  $5 per filter… that’s another unexpected $50 expense.  (Do I have to count the cost of the fish I bought when I went to get the filters?)

Ten days after buying lumber I finally had the rack up and running.  I immediately transferred the fry from all my 2.5-gallon breeder tanks into bins.  Some of the rainbow fry need heat to grow well early in life, and I realized that a submersible thermostatic aquarium heater is probably a bad idea in a plastic bin.  My room temperature stays in the mid 70’s (F), but I need to keep those ‘bows up in the 80-82F range.

I settled on trying to use commercially available heat cables that are marketed to reptile keepers.  These are rubber-coated wires that do not get hot enough to burn wood or flesh, so they will be safe for plastic.  I wanted to put the wire under the bins so the heat will rise into the water, but placing the weight of the water directly onto the wires is not a good idea.  To create a gap for the wires I placed three strips of 3/8” thick wood slats under the bins.  The wire will run under each bin twice, once in the front and once in the back.  I needed two heat cables, one for each shelf of bins, and a rheostat to control the heat of the cables (in case they get too hot).  Total cost for all that:  about $100.

To avoid having the water crush the cables, the author used pieces of wood on underneath each bin.

To avoid having the water crush the cables, the author used pieces of wood on underneath each bin.

In the end:  $770

  • $50 for lumber and hardware
  • $435 for a new air pump (it really blows!)
  • $25 for air valves, pvc to extend air system, and other ‘air supplies’
  • $30 for the bins
  • $80 for three new 10-gallon tanks with glass tops
  • $50 for filters that fit
  • $100 for heat cables and rheostat

Grow out space so I can continue to rack up spawns and bury Mike:  priceless

I am happy with the new bins.  The fry are growing fast in them.  However, it only took two weeks to end up right back where I started… too many fry and not enough tank space.  I need another rack!

Teds completed DIY fishroom rack, ready to take on more fish!

Ted's completed DIY fishroom rack, ready to take on more fish!

Posted in Breeder's Challenge and Ted Judy by TFH Magazine on November 30th, 2009 at 2:15 pm.

5 comments

5 Replies

  1. Katharina Dec 5th 2009

    Wow! You sure know a bunch. I am about to start my first attempt at breeding Corydoras Catfish. I have a 10 gallon with some other fish and a free 30-gallon. Any suggestions?

  2. Cories are my nemesis! However, most of the more common cory cats do not need a lot of tank space to breed. I would move the community to the 30 gallon and set up the catfish in the ten gallon by themselves. Good luck!

  3. Ted,

    What material are those containers made from? I’ve always avoided those types of containers worrying that they would leach some kind of toxic substance into the water. Nice setup!

    Steve

  4. I use clear polypropylene plastic containers. Look for the ’5′ in the recycle-triangle symbol on the bottom. This is a food-grade plastic, and getting clear containers ensures that there are no dyes in the plastic that can leach out. The plastic is heat resistant too, so it can be sterilized with boiling water.

  5. Sheldon Sep 1st 2010

    I’d like to know a little more about the heating cables you used. What is the wattage and length? I’m thinking of doing the same thing and I’m not what wattage would be suitable.


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