Hi Tamra,

Before you left for vacation, how did you clean the aquarium and filter? I suspect you might’ve accidentally restarted the nitrogen cycle – this can happen when you clean the tank too well – change all of the water, scrub down the glass/acrylic walls, siphon through the substrate, and switch out the old filter media. Generally, it’s fine to do these things every once in a while, but never all at once.

For example, if you’re cleaning the filter or replacing old filter media, you’ll want to only replace half of your filter media – since this is where a lot of your beneficial bacteria will grow. Or, if you’re changing the water (and siphoning out waste from the gravel), you won’t want to also replace your filter media at the same time because, again, beneficial bacteria grow in your substrate and filter.

Beneficial bacteria convert ammonia into nitrite and nitrite into nitrate. Without decent numbers, ammonia levels will rise and really stress out your fish. If you siphon out most of the beneficial bacteria from the substrate but the filter is left alone for example, your filter will still house beneficial bacteria that take the ammonia your fish produce and convert it into nitrite before the ammonia can be harmful. Remove both sources of bacteria and your goldfish might face harmful ammonia spikes. As the bacteria start to replenish itself and convert more and more ammonia into nitrite, then you have another problem – unhealthy levels of nitrite (because the type of bacteria that convert nitrite into nitrate have yet to grow to similar numbers as the type of bacteria that convert ammonia).

If this sounds new to you, let me know if you need me to clarify anything. Just know that you should never do a full tank cleaning the same day – instead, clean different areas of the tank on different days. Otherwise, you risk restarting the nitrogen cycle.

With that said, let’s get Blubby feeling better. Have you tested the water recently for ammonia or nitrite? If not, you should definitely think about doing so. You can read more about water testing in my guide here. Freshwater test kits can be picked up at your local pet store if you don’t have any on hand.

It’s good that you replaced 50% of the water. I’d continue replacing water every day until those water parameters get under control (if that is in fact the problem). If your nitrogen cycle has restarted, you’ll want to carefully monitor the water for ammonia and nitrite over the next few weeks.

Does your goldfish show any physical signs of disease (besides the obvious lethargy)? Since you did witness your goldfish swimming to the surface a few times, there’s either not enough oxygen in the water or something is preventing your goldfish from taking in enough oxygen (some goldfish diseases can affect the gills). To boost oxygen levels, you can try using an air stone (attached to an air pump with airline tubing). All of these items you can get at your local pet store. A little aquarium salt can also help reduce stress (you can read more about aquarium salt in this guide here).

Keep me updated on Blubby’s progress! And do let me know if you notice anything else. I hope Blubby starts to feel better soon!

Hi Liz,

I’m sorry to hear your goldfish isn’t eating. Loss of appetite can be caused by a number of things. To pinpoint exactly why your goldfish is no longer interested in food, I’ll need to know more about the water environment and what you’re feeding your goldfish.

Can you tell me a bit more about your aquarium? How many gallons or liters of water does it hold? When’s the last time you changed the water? Have you tested the water recently for ammonia, nitrite, and nitrate?

If not, definitely do this! Water testing is one of the first things I do when my fish look stressed out (like most fish, goldfish don’t tolerate ammonia and nitrite well at all). To learn more about this, read my water parameter guide here. I also suggest reading this guide on preventing goldfish diseases – it gives you a step-by-step break down on what to look for and actions to take when you first notice signs of stress (causing your goldfish to refuse food).

After you’ve read those two guides and followed the steps within, I just have a few more questions: namely, when was the last time you purchased food for your goldfish (yes, goldfish food does have expiration dates!) and what have you been feeding your goldfish lately?

But definitely test those water parameters! There’s likely something going on in the water that’s causing stress and stress can lead to another host of problems (bacterial, fungal, and parasitic infections to name a few). In the meantime, if your goldfish won’t eat, you can try to soak the food in Garlic Guard (or garlic juice from minced garlic – after some research, I found that it helps to use a lemon squeezer to extract the juice from fresh garlic). Goldfish love the smell and taste of garlic. The antibacterial properties in garlic also help the immune system. I personally always keep a bottle of Garlic Guard around for when I need it.

I hope your goldfish can recover! Definitely update me on those water readings.

Hi Martha,

I’m so sorry to hear about your fish. If your goldfish has a tumor, there’s really not much you can do for him outside of surgery. From what I’ve been reading, there’s no cure for most tumors. If you think your goldfish is suffering, it might be best to humanely euthanize your fish, as uneasy as the aspect of doing so is. You can try clove oil if that’s something you think you might have to do.

Otherwise, separating your goldfish from the other fish might reduce some stress – especially if the tumor is slowing your fish down or causing buoyancy issues. It won’t heal the tumor, but your goldfish can live comfortably for the rest of his life in a stress-free environment away from fin nipping – without having to compete with others for food.

But if your goldfish is swimming fine and the tumor doesn’t seem to be bothering him much, you can probably keep him in the pond. Just keep a watch on him – make sure he’s getting enough to eat and the other fish aren’t picking on him.

To better maintain the water quality in your pond, I’d suggest 30 gallons per fish at the very minimum to start with (though I have seen others recommend even 50 gallons at minimum per fish). Keep in mind, your goldfish will breed a ton in a pond. I’ve heard stories where people have had their goldfish numbers double in two or three years.

Have you tested a portion of the pond water recently? If not, it might help to know how much ammonia, nitrite, and nitrate is in the water. Dirty water is never a good sign, and it could cause problems with your other fish if not dealt with soon. Definitely get a water sample and test some of those water parameters. The sooner you can fix some of the underlying problems, the healthier your fish will be and the better their chance of recovery.

My goldfish skin is turning white and its peeling off the are eating less and also swimming less I don’t know what the problem is

It had 2 parasites, over it, which I removed 3 weeks back, water is changed 100%. fresh water is with salt added, and also added “Rid All”. during the treatment, I kept her separate in hospital tank for 1 week. all blackening had gone during the time. As the salt level was high in hospital tank.

Getting back to regular tank with others, again the blackening has returned. Fins are also getting black, shortened and torn off. even the front fins. can I post a photo on this? currently it is separated from others in hospital tank again.

She is also experiencing swim problem. some times she is upside down. doing nothing like dead. When agitated, she wakes up and runs swimming.

Please suggest the cure