Zoology Aquarium Set-up and Fish Breeding PDF

**[ZOOLOGY]** **[AQUARIUM SET-UP AND FISH BREEDING]** **1. CREATING RIGHT WATER CONDITIONS.** 1. **SOFTENING WATER** a. **Reverse Osmosis (R.O.)** ** Popular method** ** Expensive** ** Produce large amount waste water** ** R.O. Water needs to be diss...

**[ZOOLOGY]** **[AQUARIUM SET-UP AND FISH BREEDING]** **1. CREATING RIGHT WATER CONDITIONS.** 1. **SOFTENING WATER** a. **Reverse Osmosis (R.O.)** ** Popular method** ** Expensive** ** Produce large amount waste water** ** R.O. Water needs to be dissolved with tap water to maintain proper hardness** b. **Filtered Rain Water** ** Cheap** ** No waste water produced** ** Contains pollutan** 2. **CREATING A PEAT SUBSTRATE** c. ** Crush peat** d. ** Add onto water surface (5 cm / 2 in thick layer)** e. ** Let it sink** f. ** It takes approximately a week** g. ** Stirring and squeezing air filled pieces everyday speeds up the sink** 3. **HARDENING WATER** h. **Epsom salt ** ** Contains magnesium** ** No calcium** i. **Limestone-Based Rocks** ** Source of calcium carbonate** ** Aquarium Stones (Seiryu Stone and Pagoda Stone)** j. **Other Sources of Calcium Carbonate** ** Crushed coral** ** Crushed oyster she** 4. **ALTERING THE Ph** k. **Creating a peat substrate helps to acidify the water** l. **Addition of coral sand helps to increase the pH and make it alkali** 5. **FILTERS USED IN BREEDING TANKS** m. **Filters with strong current** ** Affect the small fry** ** Affect bubble nests or spawning sites** ** Not to include filters for fry** n. **Filters with soft current** ** Simple bubble-up sponge filters are best suitable for fry.** 6. **HOW TO CHANGE WATER IN FRY TANKS** o. ** Partial water changes are vital for health of fry** p. ** It helps to remove pollutants** q. ** Start with 10% changing the water per week till fry grow** r. ** After that gradually increase to 50% twice a week** s. ** Replacement water should has same hardness, pH and temperature as the tank water** **2. STOCK AND EQUIPMENT** 1. **INBREEDING** a. ** To avoid poor selection of breeding stock, obtain your stock from different sources** b. ** Exception is guppies** 2. **THE REARING TANK** c. **Tank size** ** For small fry small tanks are used** ** As the size of the fry grow transfer them to bigger tanks** ** This helps in proper growth and development** d. **Regroup** ** As fish mature, they may not be happy with large group of their own kind (e.g. Siamese fighter male)** ** Keep the group small for better resul** 3. **REARING THE OFFSPRING** e. ** Never crowd the fry** f. ** Identify and cull** g. ** Surplus the excess fry at an young age** 4. **BREEDING TRAPS** 5. **SPAWNING MOPS** h. ** Alternative to live plants** i. ** Can be sterilized before being used for breeding** j. ** Size and density can vary** k. ** Can be easily placed at the site of spawning** **3. FEEDING** 1. **INFUSORIA** a. ** The termed used for different microscopic organisms that live in water and feed on rotting plant matter** b. ** Air born spores are used** c. ** No need of stater culture** d. ** Good source of nutrition** 2. **BRINE SHRIMP** e. ** Newly hatched brine shrimp can be used as food for fry** f. ** It is supplied with the infusoria** g. ** Dried brine shrimp eggs are available from many aquatic outlets (store in dry and cool place)** 3. **MICROWORMS** h. ** Microworms can be used with brine** i. ** Need to obtain a starter culture** j. ** These worms they feed on the surface from cereal based food (Oatmeal)** **4. BREEDING** 1. **DEFINITION :** ** Breeding is sexual reproduction that produces offspring, usually animals or plants.** ** Fish breeding means the breeding, nursing and transfer of fish from one tank into another, also catching and keeping the reproducers for the recovery and maintenance.** 2. **TYPES OF BREEDERS:** i. **Live Bearers** ** Fish reproduce by bearing live young.** ** Livebearers give birth to a fully formed and functional young called fry.** ** The eggs are fertilized and hatch within the female.** ** Most livebearers have fewer and larger fry than egg layers because the fry need to be more developed and large enough to fend for themselves after birth.** ** Identifying sexes is usually easy as well. Males are generally larger and have larger, longer, more ornate, and more colorful fins than females.** ** For instance, only male swordtails have the "sword" on their tails, and male guppies have larger, more flowing tails that are brightly colored.** ** Fry should be separated from adults because the adults (including the parents) tend to eat them.** ** Small live or frozen food and crushed flakes are good for feeding fry.** ** Species of freshwater livebearers include mollies, platys, swordtails, and guppies.** ii. **Egg Layers** ** Egg layers spawn by several means, including egg scattering, egg depositing, egg burying, nest building, and mouthbrooding.** ** In all cases, eggs are laid and fertilized outside the body.** ** Nest-builders and mouthbrooders are generally good parents, protecting the eggs and fry from aggressors.** ** Many cichlid species, such as freshwater angelfish, are nest-builders.** ** Egg scatterers, egg depositors, and egg buriers may or may not defend the eggs and fry.** ** Usually the fry need to be separated from the adults to prevent the larger fish from eating them.** ** Egg-scatterer females lay sticky eggs in various places within a certain area (often in areas that provide some sort of cover), while others set nonsticky eggs adrift in open water.** ** Egg depositors pick one general spot to lay sticky eggs, usually on the bottom substrate and sometimes on the aquarium glass.** ** Egg buriers either dive into soft substrate or the male pushes the female into the soft substrate to lay. The male then dives in to fertilize the eggs.** ** In a tank breeding environment, peat moss is often a good choice for the substrate.** 3. **CARE FOR NEW BORNS** ** Fry should be separated from the adult fish and placed in a nursery tank.** ** Water conditions should be kept much as they are in the main aquarium.** ** There should be some kind of cover for the fry so they are safe, secure, and free from stress.** ** The aquarium should be filtered, but the pump should not be so powerful that it sucks in the fry.** ** Several commercial baby fish foods are available.** ** Alternatively, finely crushed flake and tiny live or frozen foods can be fed.** **\ ** **[FISH FOOD]** **1. FOOD TYPES** **Fish food can be divided into two main types:** 1. **Natural food** ** Different types of food are produced Naturally in ponds or reservoirs. These are called Natural foods.** ** They are very small and their movements depend on the direction of the water current that helps goes towards them.** ** They are know as plankton. plankton can be seen in all types of reservoirs, except for high flowing rivers.** ** Plankton is one of the Small flora and fauna whose movement capacity is So limited that they cannot cross the Stream. Therefore, in the most aquatic environments, movements of a large number of plankton species are controlled by wave and water currents.** ** Most Plankton (phytoplankton and Zooplankton can control vertical expansion through a slight movement. Some animal plankton or zooplankton can be more active and move more distances than their microbial bodies. However, their Size is so small that their movement is greatly controlled through the water current** a. **BENEFITS AND DEFICIENCY** ** Natural food has the advantage that it is easier to digest, the price is relatively cheaper.** ** it has more complete and high nutrition and the level of pollution in culture water is lower.** ** However, natural feed also has drawbacks, namely it takes a longer time to prepare it according to needs, besides that natural feed is more at risk of disease transmission go that it can interfere with the culture process carried out.** 2. **Supplementary food or artificial food.** **\ ** **[FISH DISEASE]** - **The causative factors of fish diseases can be grouped under six broad categories:** **1. Internal to the individual -- genetic diseases** **2. Environment associated diseases - (such as critical intensities of light/temperature/pH/ dissolved gases)** **3. Physical injuries (ex: handling/transporting)** **4. Nutritional diseases (ex: deficiency syndromes)** **5. Co-existing organisms (biological entities)** **6. A combination of a few or all factors** - **Diseases of fishes are caused by various types of organisms like virus, bacteria, fungi and protozoa.** +-----------+-----------+-----------+-----------+-----------+-----------+ | **Sr | **Disease | **Cause** | **Fish | **Symptom | **Treatme | | No.** | ** | | Affected* | s** | nt** | | | | | * | | | +===========+===========+===========+===========+===========+===========+ | 1. | **White | **Ichthyo | **All** | **Small | **Raise | | | Spots | phthirius | | white** | water | | | (Ick)** | parasite* | | | temperatu | | | | * | | **spots, | re | | | | | | which may | slightly | | | | | | ulcerate* | and treat | | | | | | * | water | | | | | | | with | | | | | | | commercia | | | | | | | lly | | | | | | | available | | | | | | | remedies* | | | | | | | * | +-----------+-----------+-----------+-----------+-----------+-----------+ | 2. | **Tetrahy | **Parasit | **Freshwa | | **None** | | | amena** | e** | ter | | | | | | | Fish** | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 3. | **Skin or | **Gyrodac | **All** | **Labored | **Commerc | | | Gill | tylus, | | ** | ially | | | Flukes** | Dactylogy | | | available | | | | rus | | **breathi | medicatio | | | | parasites | | ng,** | n** | | | | ** | | | | | | | | | **scrapin | | | | | | | g | | | | | | | against** | | | | | | | | | | | | | | **objects | | | | | | | ,** | | | | | | | | | | | | | | **abnorma | | | | | | | l | | | | | | | gill | | | | | | | function* | | | | | | | * | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 4. | **Neon | **Pleisto | **Neon | **Discolo | **None** | | | Tetra | phora | Tetras** | ration** | | | | Disease** | P | | | | | | | arasite** | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 5. | **Hole-in | **Hexamit | **All** | **Pale | **Metroni | | | -the-head | a | | ulcerated | dazole | | | ** | parasite* | | area | or | | | | * | | around | similar** | | | | | | head** | | | | | | | | **medicat | | | | | | | ion. | | | | | | | Use food | | | | | | | containin | | | | | | | g | | | | | | | Vitamin | | | | | | | C** | +-----------+-----------+-----------+-----------+-----------+-----------+ | 6. | **Anchor | **Lernaea | **All** | **Visible | **remove | | | Worm** | para | | ** | parasites | | | | site** | | | with | | | | | | **parasit | forceps** | | | | | | es** | | | | | | | | **and use | | | | | | **attache | medicated | | | | | | d | bath to** | | | | | | to** | | | | | | | | **prevent | | | | | | **body | secondary | | | | | | leading** | infection | | | | | | |.** | | | | | | **to | | | | | | | ulceratio | **Insecti | | | | | | n | cide | | | | | | and | may | | | | | | irritatio | help** | | | | | | n** | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 7. | **Vibrosi | **Vibro | **All** | **Discolo | **Medicat | | | s** | Bacteria* | | ration,** | ed | | | | * | | | Food** | | | | | | **reddish | | | | | | | staining | | | | | | | of** | | | | | | | | | | | | | | **fins, | | | | | | | bulging** | | | | | | | | | | | | | | **eyes, | | | | | | | lethargic | | | | | | | behavior* | | | | | | | * | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 8. | **Mouth | **Flexiba | **All** | **Cottony | **Improve | | | Fungus** | cter | | growth | water | | | | bact** | | near** | condition | | | **or | | | | s.** | | | Columnari | **eria** | | **jaws | | | | s** | | | and loss | **Use | | | | | | of** | commercia | | | | | | | lly | | | | | | **appetit | available | | | | | | e.** | ** | | | | | | | | | | | | | | **antibio | | | | | | | tics** | +-----------+-----------+-----------+-----------+-----------+-----------+ | 9. | **Fin | **Bacteri | **All** | **Erosion | **Improve | | | Rot** | al** | | at edges | water | | | | | | of** | quality | | | | | | | and** | | | | | | **fins** | | | | | | | | **feed | | | | | | | Vitamin C | | | | | | | - | | | | | | | enriched* | | | | | | | * | | | | | | | | | | | | | | **food. | | | | | | | Use | | | | | | | anti-fung | | | | | | | al** | | | | | | | | | | | | | | **treatme | | | | | | | nt | | | | | | | to | | | | | | | prevent** | | | | | | | | | | | | | | **seconda | | | | | | | ry | | | | | | | infection | | | | | | | s** | +-----------+-----------+-----------+-----------+-----------+-----------+ | 10. | **Swim | **May be | **All, | **Inabili | **Check | | | bladder | bacterial | esp.** | ty | water** | | | disease** | , | | to** | | | | | or caused | **Balloon | | **tempera | | | | by | mollies** | **balance | ture.** | | | | chilling | | in the | | | | | or | | water** | **Commerc | | | | digestive | | | ially | | | | issues** | | | available | | | | | | | medicatio | | | | | | | n** | +-----------+-----------+-----------+-----------+-----------+-----------+ | 11. | **Pseudom | **Pseudom | **All** | **Hemorrh | **Medicat | | | oniasis** | onas | | ages** | ed | | | | Bacteria* | | | Food** | | | | * | | **in | | | | | | | mouth | | | | | | | and** | | | | | | | | | | | | | | **ulcerat | | | | | | | ion | | | | | | | on** | | | | | | | | | | | | | | **body** | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 12. | **Piscine | **Mycobac | **All** | **loss | **Amputat | | | ** | terium** | | of** | ion** | | | | | | | | | | **Tubercu | **marinum | | **appetit | | | | losis** | bacter** | | e, | | | | | | | pa** | | | | | | | | | | | | | | **pules,* | | | | | | | * | | | | | | | | | | | | | | **discolo | | | | | | | ratio** | | | | | | | | | | | | | | **n and** | | | | | | | | | | | | | | **bulging | | | | | | | ** | | | | | | | | | | | | | | **eyes.** | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 13. | **Saprole | **Fungal* | **All** | **Whitish | **Vitamin | | | gnia | * | | ,** | C | | | Fungus** | | | | enriched* | | | | | | **fur-lik | * | | | | | | e** | | | | | | | | **food. | | | | | | **growths | Commercia | | | | | | ** | l** | | | | | | | | | | | | | | **medicin | | | | | | | es.** | +-----------+-----------+-----------+-----------+-----------+-----------+ | 14. | **Egg | **Fungal* | **Eggs | **Fungal | **Remove | | | Fungus** | * | Only** | growths | affected | | | | | | on** | eggs.** | | | | | | | | | | | | | **eggs** | **Use | | | | | | | Methylene | | | | | | | blue to** | | | | | | | | | | | | | | **medicat | | | | | | | e | | | | | | | the | | | | | | | hatching* | | | | | | | * | | | | | | | | | | | | | | **tank.** | +-----------+-----------+-----------+-----------+-----------+-----------+ | 15. | **Malawi | **Probabl | **All** | **Similar | **Offer | | | Bloat** | y | | to | High | | | | Viral** | | Dropsy** | Fiber | | | | | | | Diet** | +-----------+-----------+-----------+-----------+-----------+-----------+ | 16. | **Lymphoc | **Viral** | **All** | **Caulifl | **Vaccine | | | ystis** | | | ower-like | s | | | | | | growths** | may be | | | | | | | available | | | | | | **and | ** | | | | | | white | | | | | | | areas | | | | | | | around** | | | | | | | | | | | | | | **the | | | | | | | eyes** | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 17. | **Iridovi | **Viral** | **Gourami | **loss of | **None** | | | rus** | | s, | appetite. | | | | | | angelfish | ** | | | | | | ** | | | | | | | | **Darkeni | | | | | | **and | ng | | | | | | others** | in | | | | | | | color.** | | | | | | | | | | | | | | **Enlarge | | | | | | | d | | | | | | | abdomen.* | | | | | | | * | | | | | | | | | | | | | | **Occasio | | | | | | | nally | | | | | | | Lympho** | | | | | | | | | | | | | | **cystis* | | | | | | | * | | +-----------+-----------+-----------+-----------+-----------+-----------+ | 18. | **Dropsy* | **Varies | **All** | **Bloat, | **Varies | | | * | from** | | scales | depending | | | | | | stick | on the** | | | | **tempera | | out** | | | | | ture, | | | **cause** | | | | to** | | | | | | | | | | | | | | **indiges | | | | | | | tion | | | | | | | to** | | | | | | | | | | | | | | **infecti | | | | | | | on** | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ - **Heart and Blood Vessel Disorders** 1. **gas bubble disease - rise in temperature** 2. **new tank syndrome - excess ammonia** 3. **Anemia - rbc** - **EYE Disorders** 1. **EYE FLUKE- CLOUDY EYE** 2. **gas bubble disease** 3. **CATARACT - EYE FLUKE, NUTRITIONAL DEFICIENCY** - **BONE & MUSCLE Disorders** 1. **BROKEN BACK DISEASE - VIT.C & e DeFICIENCY** 2. **Pleistophora h -PARASITE ATTACKS SKELETON MUSCLE** - **Brain, Spinal Cord, and Nerve Disorders** 1. **Streptococcus infection - INFECTS BRAIN** 2. **Pseudoloma neurophilia - NERVOUS SYSTEM** 3. **new tank syndrome - eXCESS aMMONIA** - **GILL Disorders** 1. **CARBON DIOXIDE(CO2)** 2. **GAS BUBBLE DISEASE** 3. **HYDROGEN SULFIDE (H2S)** - **Skin Disorders** 1. **SUNBURN** 2. **Lymphocystis disease -cauliflower-like growths on the skin** **[AQUARIUM FISH AND THEIR MAINTENANCE]** **WHAT IS AN AQUARIUM?** **An aquarium is a glass container which displays the aquatic organisms in a simulated natural environment by introducing aquatic plants, rocks, gravels, artificial decorative etc. Maintenance of physico-chemical and biological parameters of water inside the aquaria is of utmost importance. Different types of equipments are required for controlling aeration, water movement, temperature, suspended organic matter, illumination etc inside the aquaria. Utmost care should be taken while feeding aquarium fishes. Over feeding is always harmful to fishes. In effect, an aquarium is a biological entity. Each of its elements -- water, glass, light, sand, gravel, plants, fish, make a harmonious whole, with the same ecological balance as exists in nature.** A. **SELLECTION OF A TANK** **A tank with a water capacity of 125-250 L is most conventional. An appropriate size would be an 80 cm tank (80x40x40cm) or a meter size tank (100x50x50cm). The most popular size of home aquarium is 60 cm length x 30 cm width x 40 cm height, with a capacity of 57 L (15 gallons). Never the less, aquaria size depends much on availability of space and point of attraction. Aquaria Tanks are usually measured as = Length x Depth x Height Aquarium tank is of prime importance. An aquarist must consider its shape, size and material used Tanks may be of several kinds: Metal frame tank, Plexi-glass tank , or All glass tank** B. **AQUARIA TYPES** **Based on water regime contained in the aquaria they may be of two types:** 1. **Fresh water aquaria - Aquarium that houses fish and plants of freshwater world. Freshwater contains small amount of salts and gases in solution. Fresh water may be classed as 'hard' or 'soft' according to the sodium and calcium it contains in compounds.** 2. **Marine water aquaria - Marine aquarium is a biological entity which houses marine flora and fauna in a harmony. Sea water differs from fresh water by its salt content.** **C. AQUARIA BOTTOM** **The base of an aquarium is known as bottom. Over this base aquaria bed is prepared. This serves following two basic purposes:** ** To make the fish feel more at home, and** ** To provide a growing medium for aquatic plants.** **Unless a particular species of fish has special requirements, the composition of the bed is mostly governed by the needs of the plant to be placed in aquaria bed. Plants suitable for the purpose can be grouped in** **following categories:** - **Rooted plants -- Vallisneria, Sagittaria.** - **Cuttings -- Fanwort, Hygrophilia,Ceratophyllum, Limnophila.** - **Floating Plants -- Lemna, Riccia, Salvinia** **D. AQUARIA STAND, HOOD AND PLACEMENT** - **Aquaria stand is wooden/metallic structure on which aquarium is placed. This must be flat and level and capable of carrying the load of entire set.** - **Aquaria hood is the top most covering of an aquarium to keep the fishes confined in the tank, minimize water loss by evaporation, offers more protection against intruders and helps in light attachment.** - **Placement of an aquarium should be intended to receive maximum amount of light.** **E. AQUARIA FILTERS** **Harmful substance like ammonia and nitrates are regularly produced mainly through fish metabolism as excretory product. They keep on accumulating in the aquaria water. At times, they may exceed the carrying capacity of aquaria water and cross the lethal limits and eventually poison the fish. That is why proper arrangements should be there for removing these harmful substances and getting clear water in an aquarium. This can be achieved by the process of filtration and the devices employed for the purpose are known as filters.** **Aquaria filters are of three types:** **1. Mechanical filters** **2. Chemical filters and** **3. Biological filters** **Biological filter is again broadly divided into 3 types:** - **UG filters** - **Foam filters** - **Power filters.** **Functions of filters:** - **Filters play a significant role in purification of aquaria water with the help bacteria. When ammonia loaded water is passed through the gravel bed of filter, it is subjected to the action of aerobic nitrifying bacteria that oxidize toxic ammonia into nitrite by Nitrosomonas bacteria. The nitrites get further oxidized by Nitrobacter group of bacteria into nitrates which are less toxic to the fish. They finally gets absorbed by the plants.** - **The aquaria water is quite likely to get polluted due to the excretory products of fish, plants, dead organisms and uneaten food rich in nitrogen compounds, filters get rid of them by their biological and mechanical actions.** **F. DECORATION OF AQUARIA** **Once an aquarium is well set and properly placed, now the time comes for its decoration. Uninterrupted supply of oxygen is of prime concern in an aquarium. Normally stone diffusers, connected to an air pump by a plastic tube, are placed inside the aquarium. However, to give aquaria an attractive look a number of decorative toys are available in market. They include plastic bubbles in the guise (appearance) of mermaid (sea creature), under water diver, oyster shells, angler, human skull, frog etc. Coloured marble stor sea bottom ones can be spread over the sand bottom of the aquaria. Sometimes a colorful picture of sea strata or sea bottom may be placed at back side of an aquarium to look it more attractive.** **G. WATER FILLING** **Water contributes the immediate environment for the fishes. Aquariumshould be filled with clear potable water. If tap water is chlorinated, it has to be aerated overnight before adding to an aquarium.** **H. FISHES OF CHOICE** **After maintenance of adequate water load in the aquarium (2.5cms of** **fish to each gallon of water) fishes of choice should be introduced in the** **aquarium. Aquarium fishes are both exotic and indigenous).Some of the** **popular aquarium fishes are listed below:** **(1) Barbus tetrazona and B.ticto** **(2) Betta splendens** **(3) Botia dareo** **(4) Carassius auratus (goldfish)** **(5) Colisa lalia** **(6) Colisa chuna** **(7) Cyprinus carpio** **(8) Gambusia affinis** **(9) Hemichromis bimaculatus** **(10) Lebistes reticulates (guppy)** **(11) Macropodus opercularis** **(12) Nemacheilus aureus** **(13) Poecilia reticulata** **(14) Pterophyllum scalare and P.eimekei (angelfish)** **(15) Tilapia macrocephala** **(16) Trichogaster trichopterus** **(17) Puntius ticto** **Important points to be looked into are:** **i) Regular water change (20-30% every two or four weeks)** **ii) Cleaning of algal scum from the glass at periodical interval.** **iii) Removal of dead fishes, if noticed inside the aquarium.** **iv) Racking the surface layer of the substrate and removal of dirt etc. by vacuum device every week** **v) Pruning of excess plant growth, when noticed** **vi)If aquarium water turns cloudy after one or two months, it indicates the need to change water.** **vii)Water loss caused by evaporation should be made up once a week** **IMPORTANT PERCAUTIONS FOR MAINENANCE OF AQUARIA** ** The aquarium should not be left uncared for a long time.** ** Do not over feed the aquarium fishes.** ** Once the aquarium is set and balanced, the water should not be changed unless it tends to become turbid or cloudy. When the level of water falls in course of time, it should be restored by addition of some rain water or chorine free tap water.** ** Overcrowding of fishes should always be avoided.** ** For tropical fishes, a temperature of around 720 F and pH of around 7 - 7.2 is ideal.** ** In changing the water of aquarium, a constant flow should be maintained with help of tubes.** ** Aerator should also be frequently operated.** ** Fishes should be subjected to KMnO4 or CuSO4 bath before keeping them in aquarium.** ** Aquarium should be filled by water to about three fourth of its capacity.** ** One type of food should not be used.** ** Infected fishes should be immediately removed.** ** An aquarium should always be provided with a cover.**