This section is from the book "The Goldfish And Its Systematic Culture With A View To Profit", by Hugo Mulertt. Also available from Amazon: The goldfish and its systematic culture.
The question will naturally arise in the mind of the reader, should he have any desire to engage in the culture of the goldfish, "Will it pay?" "Are the profits accruing sufficient remuneration for the time and labor expended, to say nothing of the capital invested?" To these questions the best answer is the book upon which the author has expended so much time, for he is certain that the proper cultivation of the goldfish will pay, though there are some considerations, the absence or presence of which somewhat determine the result. If looked at from a business point of view solely, it wholly depends upon the local demand for them, though more especially upon the class of customers one is expected to supply. In some places the finer qualities and varieties pay best, as the demand for them comes from a source that is both discriminating and critical, at the same time willing to pay for the very finest that can be had. Such a market is usually found in the larger cities where the wealthy classes generally reside, and it is from among them that the culturist may expect to find a ready and remunerative run of custom. In other places the demand is for quantity not so much care being taken whether the varieties are the best or not; for instance, a gentleman wishes to stock a lake upon his premises or in his garden with ornamental fish, he does not care especially to invest his money in a few choice varieties, but would rather have a greater number of a less desirable kind in order that the lake or pond may contain them in plenty, so that they can always be seen, no matter from what point.
The percentage of young grown to perfection from a given number of eggs depends altogether upon the attention paid to them, the locality in which they are raised, the season in which they are bred, and the variety to which they belong. The number of saleable fish may thus be but ten, or it may be eighty-five, realized out of one hundred eggs. The rules governing the productiveness of ponds are much the same as those that govern the crops raised from the soil.
There is this difference, however, the raising of goldfish is confined almost exclusively to the nicest season of the year, and makes it a highly interesting out-door recreation, and one that can be begun on the most humble scale at trifling expense, besides being an occupation that any lady or gentleman can indulge in with perfect propriety.