Controlling When Your Fry Swim Up

Sometimes the timing of swim-up can be seriously inconvenient.

This critically important stage, which typically lasts only a few days, might happen when you’re able to monitor your tank closely several times a day, even over weekends. Or it could occur over your school’s spring break, during the few days you are scheduled to attend a professional conference, or at a time when you need to take personal leave to attend to a sick child or ailing parent. In those cases, you’d want to reschedule swim-up, and you can do this following the procedure described here.

​The method of controlling/scheduling when your alevin/fry swim up requires you to use Tab A and C of the “Temp and DI record and swim-up calculator” spreadsheet. (First, you’ll have to download the Google Sheets file–find Download on the File menu.) Here’s a picture of the four tabs at the bottom of the Google Sheets.

After you’ve read the instructions for “Method 2: Scheduled/planned swim-up date,” click on the tab for Sheet “C. Swim-up calculator.”

In Cell B5 enter today’s date. In Cell B6 enter the date on which you want your fry to swim up. (This should be a time when you know you’ll be able to closely monitor the fry.)

Then click on the tab for Sheet “B. Temp. entry and DI record” and find the “Cumulative DI to date” (Column D) that corresponds to today’s date. Go back to Sheet C and enter that number into Cell B7. Once you hit Return, Cell B12 will give you the temperature to which your tank should be set and at which it should be consistently maintained. Here’s what Sheet C looks like.

As you approach the date on which your fish should start to swim up–perhaps beginning four or five days before the planned swim-up date–(1) remove the top and front foam insulation during the day and (2) pay very close attention to early signs of swim-up behavior. You should review the document prepared for the Idaho TIC program:

• Feed very sparingly and remove uneaten food after 10 minutes and
• Record the percentage of fry swimming up in Column E (and the percentage of fry eating in Column F) of Worksheet B. These data will allow us to refine and improve the formula we’re currently using to predict swim-up.