This was a piece of lead pipe, about two feet long, and bent in the middle into the form of the letter U.
“The water weeds are very pretty,” said Frank.
“They are,” replied his uncle, “and they are also very useful. They help to keep the water pure. I should have to change the water every day if there were no weeds in it.
Stickle-backs, Pond Weed, etc., in Aquarium.
“The whelks also are most useful. They are the road-men of our ponds and streams. They eat up all the waste matter, and so keep the water clean and healthy.”
It was great fun feeding those little fishes. They were fed sometimes on raw meat chopped very fine, sometimes on little pieces of biscuit. At first they were very shy, but they soon got over that. In less than a week they were quite at home, and would come up to the top of the water and take tiny pieces of beef from the boys’ fingers.
They would swim after Frank’s finger as he drew it round the tank, and would even leap out of the water for food that was held out to them.
At times they darted about as if playing “hide and seek” among the water weeds.
By and by the boys noticed that every time one of the little fish darted at another, the three cruel spines rose up on his back, and that he was really trying to spear his neighbour.