Fish Health - FAQ

(Frequently Asked Questions)
Health main page


Aeromonas Hydrophila
Ammonia Test Errors
Anchor Worm
Bacterial Additives
Blanket Weed
Carp Pox
Cat Damage
Costia (killer)
Common Myths
(Egg Compaction)

Fat Fish
Fish Louse
Gill Bleeding
Gill Disease
Gill Maggots
Goldfish Ulcers
Mechanical Fish
Mechanical Injury
Microscope page
Milky Skin
Mouth Cancer
My Fish Jumped
Neon Tetra Disease
pH Crash
Post Mortems
Skin Cancer
Swim Bladder
Tonic Salt
Vitamin C
Water Filters
Water Fungus
White Spot

  1. Q: When do I change the water?
    A Pond every 14 days, tank every 7 days
  2. Q: Should I leave my end filter bay dirty to let bacteria grow?
    A No, all filter bays should be kept clean at all times.
  3. Q: If I am treating my pond/tank with a parasite treatment etc. what do I do with the filters?
    A Run a by pass, never allow treated water to enter the filters.
  4. Q: In cold weather, I have a fish that floats. What can I do?
    A Bring the fish indoors (in pond water) and add 3% salt solution (cooking salt @ 1oz per gallon) at the rate of ¼ oz per day until 3% (1oz per gallon) is reached. Allow to reach room temperature. Change 50% of water in container per 5 days add 50 % of salt dose to keep at 3% solution strength.
  5. Q: Can I treat an invert marine tank with bacteria or parasite treatment?
    A No!
  6. Q: How long is a freshwater dip for a marine fish?
    A 10 minutes but monitor the fish.
  7. Q: Is a potassium permanganate dip any good?
    A No!
  8. Q: Is a salt dip for Koi at 3 oz per gallon good?
    A Yes
  9. Q: Can I treat a fish for dropsy scales, which stick out like a pine cone?
    A Yes, if you are GOD
  10. Q: If I put a canopy above my pond will it stop “Blanket weed”?
    A No, but it will slow it down.
  11. Q: Is “Blanket weed” created by sunshine only?
    A No!
  12. Q: How then do I control “Blanket weed"?
    A Don't use fresh mains water. In most cases it's the mains water that's the problem. All water entering your pond should go through mains water filters. Our blanket weed controller was developed just for this problem - keep your nitrates and phosphates down (both can be found in in mains water), and keep your filters clean. My system reached 32oC water temperature on 26 June 2006 but I have no blanket weed. My 4.600 tank is south facing with no cover - it's got nothing to do with sunshine other than if you don't control it with the latter temperatures and sunlight. Blanket Weed can grow at a meter a day.
  13. Q: Does clear water mean healthy water
    A No!
  14. Q: Is good water nil ammonia, nil nitrates and a steady pH.
    A Yes
  15. Q: What kills a Koi slowly?
    A Being on its’ own.
  16. Q: Do I need a quarantine tank?
    A Yes!
  17. Q When I build my pond do I think first about filters or the pond?
    A The filters
  18. Q: What size filters do I need?
    A As big as possible you can never be too big!
  19. Q: Do bottom drains work in every pond?
    A Bottom drains are fine if you can control blanket weed, otherwise you're in for the time of your life. Bottom drains only work in koi ponds where there is no plant debris, no leaf fall - in other words in a covered pond. They are no good where your pond backs on to a field. Do not under-rate which pump you use. Buy one with a third more power (g.p.h) for the summer months, (though you many come unstuck this summer). Just a note - 90% of fiber glass ponds if they leak, it's at the drain. The same goes for liners. Flanges are not much better. If you want bottom drains with a liner then buy a box weld but a good one. Also, bottom drains need large settling or vortex's, nothing under 6ft across - smaller ones are a waste of time and money.
  20. Q: Is it true that fish only grow to the size of the container?
    A No!
  21. Q: Is it true that Koi can live up to 300 years of age?
    A No. but many of their ancestors may have lived to a “ripe old age”.
  22. Q: Can a Koi/goldfish change colour?
    A Yes! Goldfish and koi change colour but not completely. Some reds go orange, most blues go battleship grey, black can appear where there was none, red markings can move down the body as fish grows. The fins can also colour where they were pure white, also pure white fish can turn light gold and vise versa. Along with many other variations.
  23. Q: Do Koi/goldfish jump?
    A No, only when stressed e.g.. Parasite or other problems to do with the environment in the water.
  24. Q: Do Koi lay on their side at the bottom of the pond when they are cold or asleep?
    A No!
  25. Q: Are Koi easy to keep?
    A Yes!
  26. Q: What is the best way to keep fish healthy?
    A Good water!
  27. Q: Is there such an infection as FIN ROT?
    A No, this is a form of flexi-bacteria
  28. Q: Will a plastic heron protect my fish from other herons?
    A No!
  29. Q: What is the best way to start a pond ready for Koi?
    A Put goldfish in the pond to seed the system. This is better than any man-made product.