I022 BULLETIN OF THE BUREAU OF FISHERIES. 



baskets will be shaped to the curve of the walls and will be in contact with the 

 bottom. By this means I think it will be possible for the eggs to receive the full 

 benefit of the current caused by the outlet. 



The practice of feeding fry with artificial food while they are in the hatchery 

 appeals to me as being about as obsolete and out of date as the type of box in 

 which they are hatched. Not only does the preparation of the food and its sub- 

 sequent administration involve time and trouble, but there is attached to it the 

 danger of fungoid outbreaks from the particles which have escaped the notice 

 of the fry and are decomposing on the bottom of the box. It is within the 

 knowledge of every pisciculturist that fish raised from the same batch of eggs 

 and reared luider artificial conditions always exhibit a considerable diversity of 

 growth; that is to say, there is an ascending scale of sizes running from what 

 may be described as ordinary fish to medium and large. In a natural state of 

 life, fry can and do feed whenever they are assailed by the pangs of hunger, but 

 in a hatchery they must perforce wait until the time fixed for the attendant to 

 come round and give them their food. My experience teaches me that the 

 divergence in growth to which I have referred is accentuated, if it is not increased, 

 by this intermittent feeding during the fry stage. For some time past I have 

 been using a curious little gregarious worm, the Tubifex rivulorum, which is more 

 generally known as the summer worm or mud worm, and I find that it makes a 

 magnificent food for fry from the moment they have absorbed the umbiUcal sac 

 until they are ready to go into the rearing pond. These little worms are found in 

 masses along the alluvial soil at the edges of ditches and ponds. They vary in 

 length from an inch to 3 inches and resemble in appearance animated threads 

 of floss silk. If the water above them is disturbed they will immediately dis- 

 appear by withdrawing themselves into their burrows in the soft mud. They 

 soon, however, recover from their fright, come out again, and at once recom- 

 mence the restless movements with which their numbers and bright color 

 attracted the passer-by. It is the tail end of the animal which is protruded out 

 of the mud. The skin of these worms is so fine and transparent that not only 

 can the blood be seen through it, but under an ordinary magnifying glass the 

 internal arrangements of the creatures may be plainly observed. Wlien taken 

 from the water these worms resemble to the touch a piece of very soft jelly, but 

 their full beauty is not apparent until the lump is placed in a clear glass vessel 

 filled with water, when it assumes the appearance of a magnificent scarlet 

 zoophyte, with a multitude of waving tentacles constantly in motion. 



In using these worms for feeding fry all that is necessary is to distribute 

 three or four pieces, about an ounce each in weight, at different parts of the 

 rearing box, and the fry will commence feeding upon them and will require no 

 further attention. Fry so reared make better blood and better bone than those 

 brought up on artificial food in the usual fashion, and, unlike the latter, they 



