Trout in the Classroom

Trout in the Classroom Update 11/6/2015: The trout are up and swimming!

We welcomed the addition of 233 trout eggs to our lab tank on October 6. Several hatched immediately after delivery and the rest did so throughout the remainder of the first week.  Not all the eggs survived, which was to be expected, and we had a hatch rate of 77%. For the first three weeks, the baby fish, called alevins, were not very exciting to watch. During this stage of their life they lie motionless on the bottom of the river while they develop and begin to grow.  The alevin do not even eat and instead absorb nutrients from the golden yolk sacs on their round bellies.  

Pictured above are the eggs in their hatching basket.  The hatching basket keeps the babies accessible and visible for the first few weeks of their life.  The solid white eggs are ones that died and began to grow fungus.  We had to remove the dead eggs each day to prevent the fungus from spreading to the healthy eggs.  In this picture, a few alevins that have hatched are visible with their round yolks sacs on their belly.  

This week, the silvery little fish, now called fry, depleted their yolk sac and rose from the bottom of the tank in search of food.  They are learning to swim against the current and to come to the top of the water column to eat just as they would in the wild.  They do not need much food yet as they are only a few centimeters long, but we have begun to feed them tiny pinches of special high protein fish flakes that the Department of Game and Inland Fisheries provides to us.  In the wild, brook trout eat insect larvae called macroinvertebrates as well as other small fish and even salamanders as they grow larger.

As the fry eat and grow, they will begin to produce waste which can build up in the tank and cause water quality issues.   Students in Mrs. Bement’s chemistry classes did the first water quality tests of the year to make sure that the water was clean enough for the fish to thrive.  As expected, the fish are too small to produce much waste yet but as they grow we will need to test more often and begin doing partial water changes in the tank.  We entered our data on the Virginia Trout in the Classroom website so that data can be shared and compiled between schools: https://sites.google.com/site/troutintheclassroomdata/virginia  It is great to be part of the TIC collaboration!