152 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
the second pair of fish had cleared a similar space, a pint or more of gravel was 
scattered. on the nest; the fish immediately began to remove the stones, and in a few 
minutes had completely freed the nest from gravel. The gravel- regarded by bass 
and other fishes as desirable material for the bottom of nests— may be removed by the 
cat-fish for two reasons: (1) To have a clean place for the eggs and young, so that they 
may be better guarded and agitated as hereafter described; (2) to provide a smooth 
place on which to rest and against which to rub the abdomen. 
Upward of twenty years ago the yellow cat-fish was much more abundant in 
the Potomac River than at present. The marshes in Piscataway Creek were a favorite 
place for the fish to spawn, and large quantities were there taken each season in 
spring and summer, mostly by colored people living near the river. The fish at that 
time of year were found in shallow water occupying depressions in the muddy bottom, 
with most or all of their bodies concealed in an excavation extending laterally from 
the rounded depression. The fishermen easily made large catches by wading and 
thrusting their hands into the depressions. An old colored man whom we knew used 
to refer to a marsh as his “meat market,” and would often bring ashore a sackful 
of yellow cat-fish caught in this way. We are inclined to believe that these fish were 
brooding, but we have had no opportunity of late years to examine them critically. 
Behavior of adult fish before spawning. — Two days intervened between the 
beginning of the nest-making and the laying of the eggs. As soon as the nest was 
made ready, the fish became very quiet. During most of the time they rested on 
the bottom, with practically no body or fin movement, except at intervals. The fish 
lay close together, often parallel, with their abdomens just clear of the bottom, their 
weight being borne on the anal and ventral fins. At frequent intervals the female 
compressed her distended abdomen against the smooth slate bottom with a quivering 
or convulsive movement, the male often accompanying or following the female in 
this action, which is obviously for the purpose of loosening the eggs. 
The second pair remained on the nest from July 18 to September 30, when they 
were removed to make room for other species, as it was evident no eggs would be laid. 
During this time they behaved in the same way as the other pair and their failure to 
spawn can not be positively accounted for, though such an outcome has been the 
rule among fish retained in the Fish Commission aquarium. The enlargement of the 
abdomen and ripening of the eggs go on to a point when spawning seems imminent; 
the actions of the fish suggest the arrival of breeding time; but no eggs are laid. 
After a few weeks the enlargement of the abdomen subsides, and dissection has some- 
times shown a liquefaction of the egg mass. It has been suggested that the presence 
of alum in the circulating water has an injurious astringent action on the mucous 
membrane of the vent, and it is a significant fact that the change from an open to a 
closed circulation, with consequent elimination of the alum filter, was soon followed 
by the spawning of the cat-fish first mentioned — an unprecedented occurrence at 
the Fish Commission aquarium. The second pair of fish had been in the alum- 
filtered water for a few days, some time before the spawning season. 
Number , character , and incubation of eggs. — On July 5, between 10 and 11 a. m., 
the eggs were deposited in four separate agglutinated masses on the clean slate bottom. 
Unfortunately, the fish were not under observation at this time, although they were 
watched for about fifteen minutes after the extrusion of the first two lots of eggs, 
when it was supposed the spawning had been completed. The masses of eggs were 
of nearly uniform size, about 4 inches long, 21 inches wide, and half an inch thick. 
The newly laid eggs are one-eighth of an inch in diameter, nearly transparent, and of 
