my ill goldfosh

Question
hi my goldfish is ill, this is now my third goldfish, the other two died after about two weeks and my current goldfish is only a week and a half old. He's a shubumkin and now no longer swims he just sinks to the bottom of the tank. he never lifts off the gravel, he look sa absolutely fine on the outside with no visible defects. My first goldfish got a really bad fungus all over its back and mouth (it wasn't a shubumkin) the second was a lemon goldfish that looked as if it had fin rot and then it just died. I feed this goldfish on improvit frozen fish food once a day but i have now cut down to every other day as i thought the ammonia and nitrite may be too high, these i have now checked and they are both clear. the pH is at about 8.0 to 8.5 and the nitrate is fine. I have also been doing regular water changes, and conditioning the new water. I am now treating the water with myxazin. The tank size is 70litre, and this is the only fish i have in the tank. i really don't understand what i am doing wrong, many thanks Lucy.

Answer
Good evening Lucy,

I'm glad to hear that you are doing regular water changes and water tests, that's essential. About how much water are you changing weekly? Goldfish breeders change about 90% per week, 50% water changes weekly would be just right, in my opinion. Goldfish are very messy and need a tank with ample filtration, 6 times turnover would be my recommendation. Since your 70 liter tank is roughly 18.5 gallons, you should look for a filter rated at 110 gallons per hour (gph).

One thing that jumps out at me is that your pH is high, and seems to swing considerably. pH shock is awfully stressful for fish, and since the pH scale is based on algorithms of 10, a difference of .5 is actually a 50 times difference! Goldfish are highly adaptable in terms of pH, 7.2 is generally considered ideal but anywhere from 6-8 pH is acceptable. What is the pH level right out of your tap? This is the level it should stay at, with no more than .1-.2 points deviation. If your pH is being driven down that much, you may be waiting too long in between water changes. Organics build up in the water, driving down pH. Again, make sure you are changing a sizeable percentage of water weekly.

Unfortunately, while it is fairly easy to buffer up your water, it is difficult to soften the water consistently. Water of a high pH is often hard and alkaline, and tends to resist change. You could use natural peat in a stocking in the filter or add untreated driftwood to the aquarium, but these might stain your water - you might not find that aesthetically pleasing. Either of these techniques would slightly soften your pH gradually and naturally. In any case, I doubt pH is the root problem here. I'll tell you what I speculate and give you a few suggestions.

Goldfish are primarily vegetarians. Improvit is not a brand I am familiar with - it's not a brand commonly available in the U.S. - and while what I've read of it online would imply to me that it's fine to offer a few times a week, no frozen food diet is entirely complete. What I read on one site about how "1 pellet a day gives your fish all the necessary nutrition" seems a bit Jetsons like. You must offer other foods for your goldfish's health and prosperity. While an unbalanced diet usually does not pose immediate health threats, feeding a high protein diet or an exclusively prepared foods diet will cause nitrates to go up right away, and this factor does have a direct effect on health and immunity. Read here about how to expand the diet:
http://www.wetwebmedia.com/FWSubWebIndex/gldfshmalnut.htm
http://www.kokosgoldfish.com/food.html
http://www.goldfishinfo.com/feeding.htm

Not only will this these suggestions help keep your water fresher and keep your nitrates down, it will be much more nutritious and healthy for your goldfish to have fresh vegetables and aquatic plants in addition to prepared foods. So these are my suggestions:

1. Change 50% of the water weekly. Since you've already administered medciation, well if it works, that's fine, but very likely your fish is sulking from environmental factors. Maybe a bit of aquarium salt and Epsom salt at 1 teaspoon per 10 gallons (38 liters) would help to perk him up. Salts help with osmotic stress and are helpful with buoyancy problems - not sure this is the case here, but it wouldn't hurt to try a small amount of salts, in this case.  

2. A change in diet is definitely called for. Alternate the frozen food you are feeding with aquarium plants and vegetables. The first website lists plants extensively, those last two websites list vegetables extensively. Frozen foods such as vitamin or spirulina enhanced brine shrimp, daphnia, and bloodworm can be offered as treats 1-2x weekly.

3. Test your water regularly while you are medicating. Medication affects the biological filtration in your tank. What do you have in your filter that provides biological filtration? I use a combination of foam sponges and ceramic media in a media bag. Once in a while I use a layer of filter floss as a pre-filter. I don't very often use activated carbon in freshwater tanks - once in a while I will use a 10 oz. bag of Chemi-Pure which is activated carbon and resins in a nylon bag. It lasts 3-4 months.

4. Lastly, what are your nitrates? Here in the U.S. we maintain that levels above 20 ppm are unhealthy, the lower the better. However my test kits say that 200 ppm is "acceptable"! It's true that nitrate is by far the least deadly in the nitrification process, but even nitrate - the end product of the nitrogen cycle - has an adverse effect on fish. I have read of and helped folks with many accounts of unexplained bumps and lumps, outright tumors, lack of appetite and overall vitality that was traced back to high nitrates. So no matter what your test kit says, try to keep nitrogenous waste build-up to a minimum. Your tank is fine for one goldfish - bigger would be better - but in this relatively small space nitrogenous build-up happens quickly and must be offset with large weekly water changes.

It sounds like you are doing your very best, thank you for being such a conscientious aquarist! Try my suggestions and see if they work. Stepping up water changes, expanding the diet may be all your goldfish needs. Keep in mind that the "fancy" varieties of goldfish are not nearly as hardy as their common brethren, but feeder fish are not ideal specimens in an aquarium, either. Their poor genetics and poorer rearing conditions predispose them to growths and abnormalities such as bent spine, lockjaw, and nearly always, premature deaths. Ensure that you are administering the best husbandry possible to rule out environmental illnesses, and medicate only as a last resort.  

I hope that helps, take care!
Nicole