File:Gambusia affinis (Top minnow) male (19356792672).jpg

Title: Annual report of the Commissioner of Fisheries to the Secretary of Commerce for the fiscal year ended ..
Identifier: annualreportofco1917unit (find matches)
Year: 1919 (1910s)
Authors: United States. Bureau of Fisheries
Subjects: Fisheries
Publisher: Washington : G. P. O.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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4 MINNOWS GAMBUSIA AFPINIS AND CYPKINODON VARIEGATUS. This fish is one of the hardiest known to the writer. It flourishes in very stagnant water, providing, of course, that the proper amount of food is available; it thrives in the aquarium; and it lives equally as well in salt as in fresh water. It may be plunged directly from the one mto the other without any apparent harm. If placed in a battery jar and left without change of water it will usually survive until a green scum forms on the walls of the contamer; thereafter no more attention need be given it, except to add a small quantity of water from time to time to compensate for evaporation. Care must, of course, be exercised not to give the fish more food than it can consume. Probably more aquarium fish of all kmds are lost through overfeedmg than from any other cause. Both old and young have been kept in the aquarium at the laboratory for one and one-half years, and were stiU in good condition at the expiration of that period.
Text Appearing After Image:
Fig. 1.—Gambusia affinis. Top minnow. Male. Gambusia becomes inactive and ceases to feed even during mod- erately cool weather. It is at its best in water of a relatively higlj temperature. The shallow water in which it is usually found in abundance during the smnmer reaches a temperature, durmg the day, which is above that of the human body. It is never a very active swimmer, and when it ventures out into water inhabited bj^ larger fishes it becomes an easy prey. Its habit of swimming at or near the surface is well known, and this has caused it to be known every- where throughout its range as the top minnow. When in very stagnant water it projects its mouth above the surface at frequent intervals, making a suckmg noise each time. It is presumed that this is done because there is an insufFicivint supply of free oxygen in the water, but if this is the case the deficiency of oxygen does not appear to interfere with the health and welfare of the fish. The large size attained by the minnows in the stagnant pond on Gallants Pouit may be cited as evidence.

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