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Stuff Every Fish Owner Should Know

Freshwater aquariums: the nitrogen cycle, tank size, water testing, goldfish myths and betta care.

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  1. How long can a well-cared-for goldfish live?
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    30 years or more. Goldfish can live 30 years or more, according to the Southern Regional Aquaculture Center. A child getting one may still need an adult plan for its care decades later.

  2. How large can a goldfish grow?
    Show the answer

    Nearly 23 inches. The Southern Regional Aquaculture Center says goldfish can grow nearly 23 inches long. Plan the aquarium for the fish's adult size, not its size at the store.

  3. Does a small tank set a healthy maximum size for a goldfish?
    Show the answer

    No, larger fish need more room. Goldfish do not neatly grow to fit a tank. Rutgers Extension says larger fish need larger tanks to reach full size, and SRAC says goldfish can grow nearly 23 inches. Plan for adult size.

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  1. How long can a well-cared-for goldfish live?
  2. How large can a goldfish grow?
  3. Does a small tank set a healthy maximum size for a goldfish?
  4. Should a goldfish be treated as a disposable pet?
  5. Why can goldfish be a poor match for many tropical fish?
  6. Tropical aquarium fish need water kept near what temperature?
  7. Does a goldfish tank usually need a heater?
  8. What does a betta need for long-term health?
  9. Can an 8-year-old be solely responsible for an aquarium?
  10. Does a betta fish need a heater in most homes?
  11. What size home does a University of Illinois vet recommend for one betta?
  12. What is the main problem with keeping a betta in a small bowl, according to a vet?
  13. What kind of filter is best for a betta's tank?
  14. Can two male bettas share a tank?
  15. Can a betta live by nibbling plant roots in a vase?
  16. How can bettas breathe air at the water's surface?
  17. If you want to add snails or shrimp to a betta's tank, what has to change?
  18. A common freshwater stocking guideline is 1 inch of fish for every how much water surface?
  19. Compared with a warm tropical tank, should a cold goldfish tank hold more fish or fewer?
  20. Why does a saltwater tank hold fewer fish than a freshwater tank of the same size?
  21. About how much does 1 gallon of aquarium water weigh?
  22. Where should you NOT put a fish tank?
  23. Is a small bowl less work than a bigger filtered aquarium?
  24. Which aquarium takes the most maintenance?
  25. Is buying the fish the only aquarium cost?
  26. Which aquarium chore is on the DAILY list?
  27. Which of these is a WEEKLY aquarium chore?
  28. What should a family do BEFORE buying any fish?
  29. What should happen before fish enter a new aquarium?
  30. When choosing a fish at the store, which sign means it is probably healthy?
  31. Per the CDC, which kids should NOT clean or handle aquarium items?
  32. Before changing water in the tank, what should you do with the filter, light and air pump?
  33. What does a pet fish depend on you for?
  34. Why does water temperature matter so much to a fish's body?
  35. Why put a cover on a fish tank?
  36. What do beneficial bacteria turn ammonia into first?
  37. What do nitrifying bacteria turn nitrite into?
  38. Which nitrogen waste is the least toxic to fish?
  39. Which form of ammonia is far more toxic to fish?
  40. Why is nitrite dangerous to fish?
  41. What does cycling a new aquarium mean?
  42. A fishless cycle adds what instead of fish?
  43. What does fish-in cycling require from the owner?
  44. What causes new tank syndrome?
  45. Which water tests matter most during a new tank cycle?
  46. What do most aquarium ammonia test kits actually measure?
  47. How is nitrate removed or reduced in most home aquariums?
  48. About how much tank water is a common weekly partial water change?
  49. Why should you avoid replacing all the tank water at once?
  50. Why do you add dechlorinator to tap water?
  51. What should you never use to clean aquarium gear that goes back in the tank?
  52. What does mechanical filtration do?
  53. In an under-gravel filter, what acts as the filter?
  54. What does chemical filtration often use?
  55. What happens to beneficial bacteria if the filter stops for many hours?
  56. How should you rinse mechanical filter media?
  57. Which condition do most tropical fish prefer?
  58. Why float a new fish bag in the aquarium before release?
  59. Why does every heated aquarium need a thermometer?
  60. What does aquarium pH measure?
  61. For many freshwater fish, the deadly pH limits are about what?
  62. Which pH change is most dangerous for aquarium fish?
  63. How can overfeeding worsen water quality?
  64. How much food should you give fish at one feeding?
  65. What should you do with uneaten food after feeding?
  66. About how long can a new aquarium nitrogen cycle take?
  67. What levels of ammonia and nitrite are safe in a cycled aquarium?
  68. What often happens to pH in an established aquarium between water changes?
  69. Does one feeding schedule work for every kind of aquarium fish?
  70. How long should dried fish food be kept on hand, according to Merck?
  71. Your tank test shows ammonia. What is the first thing to do, per UF/IFAS?
  72. What quarantine period does Merck give for valuable pet fish?
  73. During quarantine, you add another new fish to the quarantine tank. What happens?
  74. When adding new fish from the store bag, what should you do with the bag water?
  75. How can you keep new live plants from bringing ich into your tank?
  76. Your fish has tiny white dots like grains of salt on its fins. What is a likely cause?
  77. Why must ich be treated more than once?
  78. What does even a low level of ammonia do to fish over time?
  79. A fish's fins look ragged and frayed. What does Merck list this as a sign of?
  80. Which fungus does Merck link to grayish-white, cotton-like growths on fish?
  81. What does dropsy describe in a fish?
  82. Which of these does CDC list as a sign of a sick fish?
  83. Your fish hides and holds its fins tight against its body. What does that suggest?
  84. A fish keeps swimming at the surface trying to gulp air. What does Merck call this?
  85. Per Merck, most home aquarium emergencies are caused by what?
  86. Merck says aggression toward newly added fish is common among which freshwater fish?
  87. According to CDC, when should you wash your hands around pet fish?
  88. Where does CDC say NOT to dump tank water or clean aquarium gear, when possible?
  89. You have a cut on your hand and need to clean the tank. What does CDC advise?
  90. Germs called Mycobacterium can cause fish tank granuloma in people. Where does it usually show up?
  91. Can a fish that looks perfectly healthy still spread germs like Salmonella to people?
  92. You can't keep your fish anymore. What does CDC say about letting it go in a pond or river?
  93. Which is a good way to rehome a fish you can no longer keep?
  94. How should you get rid of unwanted aquarium plants?
  95. In Minnesota, may you release a pet goldfish into a lake or pond?
  96. Someone else will feed your fish while you're away. What does Purdue's 4-H guide advise?
  97. Are there veterinarians who treat pet fish?
  98. Do pet aquarium fish usually get vaccines like dogs do?
  99. One fish in your tank looks sick. Where does Merck say it can be watched and treated more easily?
  100. While fish are in quarantine, which gear should be used ONLY for the quarantine tank?
  101. According to Merck, what makes a simple, low-cost home quarantine tank?
  102. A storm may knock out your power soon. What feeding change does a UF fish vet suggest?
  103. You will be away for several days. What does a Texas A&M goldfish guide say you can do?
  104. If you stop feeding your fish, do they stop making ammonia?
  105. How does cooler water change how much a goldfish eats?
  106. The power goes out. What keeps oxygen getting into your aquarium water?
  107. The power comes back after an outage. What does Florida Sea Grant say about feeding?
  108. During a summer power outage, your tank gets too warm. What does a UF fish vet suggest?
  109. In a long power outage, how can you keep your filter's helpful bacteria alive?
  110. For emergencies, how much extra treated water does Florida Sea Grant suggest keeping on hand?
  111. Many cities treat tap water with chloramine. What is chloramine?
  112. Your home uses a private well. Does its water usually contain chlorine or chloramine?
  113. Before pouring new water into the tank during a water change, what should you check?
  114. Stocking a brand new aquarium: how does Merck say it can be good to add fish?
  115. While a new fish's bag floats, what simple trick does Merck suggest to calm territorial tankmates?
  116. Tiger barbs are fin nippers. Which tankmate does a Wisconsin 4-H guide say they should not live with?
  117. Is it OK to leave aquarium lights on 24 hours a day?
  118. Green algae keeps growing on the glass. What change does a Wisconsin 4-H guide suggest?
  119. Setting up a new tank: when should the filter, heater and pump be turned on?
  120. Per Purdue's 4-H guide, which usually costs more to get started?
  121. Which of these should you be careful about using on yourself or near your aquarium?