largissime veniant, quoniam modus ille aquae iacentis infra libram maris non aliter exprimitur, quam si 5maior recentis freti vis incesserit. Multi putant in eiusmodi stagnis longos1 piscibus recessus et flexuosos in lateribus specus esse fabricandos, quo sint opaciores aestuantibus latebrae. Sed si recens mare non semper stagnum permeat, id facere contrarium est. Nam eiusmodi receptacula nec facile novas admittunt aquas, et difficulter veteres emittunt: plusque nocet putris unda, quam prodest opacitas. 6Debent tamen similes velut cellae parietibus excavari, ut sint, quae protegant refugientes ardorem solis, et nihilominus facile, quam conceperint aquam, remittant. Verum meminisse oportebit, ut rivis, per quos exundat piscina, praefigantur2 aenei foraminibus exiguis cancelli, quibus impediatur fuga piscium. Si vero laxitas permittit, e litore scopulos, qui praecipue verbenis3 algae vestiuntur, non erit alienum per stagni spatia disponere, et quantum comminisci valet hominis ingenium, repraesentare faciem maris, 7ut clausi quam minime custodiam sentiant. Hac ratione stabulis ordinatis aquatile pecus inducemus; sitque nobis antiquissimum meminisse etiam in fluviatili negotio, quod in terreno praecipitur: Et
the flow is very abundant, since the quantity of water which lies below the level of the sea is only forced out by the greater violence of the fresh sea water rushing in. Many people think that in the5 sides of ponds of this kind deep recesses and winding caves should be constructed for the fishes, so that there may be shadier places of retreat for them when they feel the heat. But if a change of sea water is not continually passing through the pond, the result is to cause a contrary condition, for lurking-places of this kind do not easily admit a change of water and only with difficulty get rid of the stale water, and more harm results from the putrid water than benefit from the shade. There ought, however, to be6 excavated in the sides of the pond what may be described as a series of similar cells which may serve to protect the fish when they want to avoid the heat of the sun and yet at the same time let the water, which they have received, easily flow out again. It will be well to remember that gratings made of brass with small holes should be fixed in front of the channels through which the fish-pond pours out its waters, to prevent the fish from escaping. If space allows, it will not be amiss to place in various parts of the pond rocks from the sea-shore, especially those which are covered with bunches of sea-weeda and, as far as the wit of man can contrive, to represent the appearance of the sea, so that, though they are prisoners, the fish may feel their captivity as little as possible.
Having arranged “stalls” for them on this7 principle, we shall introduce our “water flock” into it, and it should be our prime concern to recall also in our dealings with rivers the advice given for our business with dry land: “And consider well what every