MARINE NATURE NOTES.

Otago Daily Times, Issue 21196, 29 November 1930, Page 2

MARINE NATURE NOTES.

Written for the Otago Daily Times.

By David H. Graham, P.Z.S.

Biologist to the Marine Fisheries Investigation and Biological Station, Port Chalmers. HOW TO WORK A MARINE AQUARIUM. Schoolmasters and school children have frequently asked me if a sea-water aquarium on a small scale is- possible, the method, of conducting one, and dangers to avoid. There is' no reason whatever why adults or children should not participate in the. endless pleasure of keeping a few marine animals. The pleasure of an aquarium is greatly increased if the owner will keep some definite objective in view, such as following the development or life history of one particular kind. of animal and taking notes and drawings of them in various stages, thus adding to our knowledge of marine life. To such an owner dullness is an unknown quantity. He will derive endless pleasure that will cause him to agree with Milton when, the poet composed .those lines: — Wonderful Indeed are HI« works, Pleasant to know, and worthiest to be all ■ Had In remembrance always with delight 1 ; But what created mind can comprehend Their number, or the wisdom Infinite .That brought them forth, but hid their causes deep? Those within easy reach of the sea wiu have no difficulty in keeping an aquarium in good working order and formas a delightful and stimulating hobby. But those further, inland need not despair, as it is quite possible to work an aquarium by using artificially-made ’ salt water, borne may doubt this statement, but when one remembers that there are several aquaria in England in which salt water made from chemicals is used, one of them u ™g over 200,000 gallons constantly, it will be seen that the recipe must be practical. To make a success of an aquarium there are several rules that the owner must follow out with the greatest zeal. They are aa follow;—Cleanliness; not too many animals in one container—far better too few than, too many; strict attention to aeration, which is the life of the animals as. much as air is to us; and others of minor importance, all of which will be dealt with later on in this article. The first matter to consider is the tank Glass, o£ course, is beet if we wish to see the inhabitants ns they appear, and not simply as when viewed. from above. A four-sided glass tank with a sloping bottom.is the best, as it enables one to see the inmates easily, and the sloping bottom allows different animals to resort -to varying depths. But almost any kind of container will answer the purpose. Show glasses, gold-fish globes, crockery, pans, ‘ or even the bedroom wash basin, will all answer our purpose and give an opening for display of taste and ingenuity. When one has obtained a. tank it is necessary to see that J® i|, quite.clean, and three-parts should be filled with clean sea water. Here, I nmy add a word of warning. Do not be satisfied with anythingbut the cleanest of sea water, A/quantity' taken *from a rocky parti of the coast is preferred to that taken from the shore, where mud is stirrred up by the incessant turmoil of' waves. Further, , see that the' container used to carry the water to the aquarium is of the deadest. Do . not make the mistake' I once did—of carrying water in a Jar which, as I. found out afterwards fwnenall the animals died),.had a cork' that was once used as a stopper for chemicals. When the sea water is collected obtain a few acorn barnacles from the rocks and introduce these in the aquarium with the sea water. These, animals are’ the safeSuard in introducing further animals. If . ae barnacles continue active by contracting. and displaying their sensitive feelers, which are really legs, we can rest assured all is well, and proceed,to the shore for our specimens. The next duty is to obtain .a small rock or stone on which is growing a.green seaweed (ulva) or sea lettuce. This weed is most essential. The proportion of seaweed to the size of the bowl and number of animals it contains can only«be ascertained by tests. This seaweed in the aquarium is important, as it gives off oxygen which is necessary to the life of the animals,'and at the same time consumes the carbonic acid gas given off by the animals. The need for plants and animals to live together will be readily understood. Next, collect a few small stones and some sand, see that both are perfectly clean and not with mud amongst them. The stones will depend on the size of the tank. Arrange these at the bottom of the bowl; they are for the comfort and well-being of tile inmates, who delight in climbing over cr under them. .. The tank is now ready for the specimens filled with pure, clean. sea water, a plant of seaweed giving off oxygen and the barnacle's active and feeding. Our next duty is to,introduce an odd scavenger or two to check the growth of microscopic animals and plants, which will soon begin to grow on the sides of containers. An ordinary periwinkle or two, or a sea slug, will answer the purpose excellently. The most beautiful inhabitants with which to stock an aquarium without any doubt whatever, are sea-anemones. At the same time they are among tbo easiest to keep. They ore to be found in various colours, in crevices or under rocks - around our coast.. Being, of a sedentary nature they are highly suitable for small aquaria. Another. point is that they need feeding only occasionally, for sometimes after a feed they refuse one again for weeks. Being of a hardy nature they will endure captivity under the most trying circumstances. A few sea slugs of various colours are also interesting and of little trouble, feeding on seaweed and spores on the sides of the containers. Should these molluscs be kept till they spawn, which is in the form of a ribbon, one will be amply repaid for one’s trouble. Other animals and seaweed may be added occasionally according to thq size of the aquarium and in accordance with individual taste. The selection of the specimens leaves for the owner ample room for. allowing his fancy to clothe the tank with seaweed that can be found growing on rocks like tapestry. • Others, that like the broad banana' growing, Raise their long wrinkled leaves ot purple hue Like streamers wide outflowing; .Trees of the deep, and shrubs, and fruits, and flowers, ' Aa fair ns ours, , Wherewith the Sea-nymphs love their hair to braid But once again do not overcrowd; far better too few specimens than too many, or the owner will court failure. Better still, once he can manage one tank, attempt another on a different scale. For a suggestion I .would recommend one tank with seaweed and a few shellfish, and if a female crab with eggs can be found the owner, will have an interesting and instructive time following out its movements. For another tank, a few small cock-a-hullies and seaweed; but as in other hobbies individual tanks can better be expressed to suit the owner. To aid the aeration of the tank I would suggest obtaining a cheap syringe,' to' be filled from the seawater in the tank, and emptied by injecting the water back again at, say, a distance of six .inches or so from the surface. If this is done several times a day enough air will be carried back into the. water to keep it well supplied with oxygen. Do not keep the tank in a bright, sunny situation; rather, keep it in a shaded place, away from direct glare of the sun. For food, small pieces of meat or fish will answer the purpose, but be sure to remove any that is left as decomposition soon sets in and causes trouble. If the tank is kept scrupulously clean, not overstocked, and well aerated with the syringe fhe sea water will keep sweet for some time, but if the owner lives neat the sea I would recommend changing the water once a week, or more often if he wishes, as the fresh sea. water will bring fresh food to the specimens. Do. not be dismayed if certain of the specimens do not stand the ordeal of being domesticated, for some are sure to die in,a few days, and others will linger perhaps a week, hut keep on trying, and those will soon he found that will acclimatise themselves to their surroundings,. and, with reasonable care, last indefinitely. I now propose to give some genera! warnings and pitfalls that one is likely to fall into, thus helping one over the rocks on which I fell. Don’t take cloudy or dirty water to the aquarium. Don’t ■be tempted to overstock, as a small number of animals in perfect condition is far more interesting than a lot of sickly specimens slowly dying off. Don’t leave dying specimens in the tank. Don’t put specimens in together that are unsuitable to each other—ones that either prey on each 'other, or fight. Don’t forget to attend to the tank twice or three times a day for a few minutes. Don’t forget to aerate the water frequently; if there

is. no time to use the syringe, stir the water quickly with a rod or fork. Don’t add pieces of rock or weed with, dirt or black col&uring matter on them, as this has a deteriorating effect on the specimens. Don’t add fresh salt water to old; draw off the old first, then quietly add the fresh. Don’t let the water evaporate below a certain level, but, if it does, add fresh water to make it up to the original height. Don’t keep the aquarium in the direct sunlight. Don’t add slimy seaweed at any cost, as that might mean the death of all the specimens. Don’t be afraid to experiment with an extra tank, noting the effect. Don’t over feed or leave uneaten food about the stones.. Don’t be disappointed if at first there is no success. Don't only keep an aquaria for fun; study its inhabitants and the joy of observing will be realised. Don’t use deep vessels for aquaria; shallow ones are the best, as more surface means more oxygen, and likewise easier to examine. Don’t forget to take copious notes of observations and experiments. The, Chinese and Japanese. have worked aquaria from -the earliest times, keeping domesticated fish for their pleasure. It was the ancient Romans who caused channels to be excavated from the seashore in order that fresh sea water could come in at high tide to their villas, where magnificent ponds, containing marine animals, were kept. No trouble was too great, and many intricate and expensive ponds were made. A pond in a banqueting hall was no uncommon feature amongst them. These ponds were made in order to enable.the guests to see the fish caught and prepared for the feasts. The Romans were especially fond of rearing red mullet, which gave them ‘a great deal of amusement-at these banquets when the. mullet was caught the guests took a delight in watching it die, for this fish in its death agonies would change to the many colours of the rainbow.. In fact, the rearing of this fish was so much in vogue as (like the orchid fever) to become a passion, for wo read of a person in the time of Caligula paying as much as £240 for a single red mullet. It is also recorded that the ponds of Cceaar Caligula, in A.D. 40, were sold for bo less A sum than £30,000. • of my readers who intend to keep an aquarium must, although there are few hobbies less, troublesome, be prepared to spend a little attention to it, and that attention must be given daily. A few minutes a day will suffice—just long enough to see there is no deaths or, decay. If there is, remove the dead fish and don’t forget to aerate the water. Should any readers find any difficulties they cannot overcome, I shall be pleased to assist and advise to the beat of my ability. If any country readers feel envious of those near the seashore, let me' advise, them to try a fresh water aquarium, for many a pleasant and profitable hour I have spent with one. i