Top 10 Mistakes New Fish Owners Make – #5

The #5 Mistake – Not Understanding Filtration

Mastering the ins and outs of filtration in aquatic systems can seem a daunting task for new owners, but we’re going to make it SO EASY!! To start out, there are three types of filtration going on in your fish system:

  • Mechanical (floss, sponges, pads) – These components remove particulate from your aquarium. They need to be cleaned regularly to maintain water flow rates throughout your aquarium.
  • Biological (bioballs, ceramic media, strapping, floss, sponges, media bed) – These provide housing for your good bacteria that keep your nitrogen cycle running smoothly. They need to be cleaned carefully so you do not remove too many of them.
  • Chemical (UV, carbon) – These components change the action of particulates in your water. UV lights kill algae and carbon will alter any chemical treatments added to your tank. UV light has NO EFFECT on bacteria or parasites living on your fish.

When you clean your tank, understanding what each part does will illustrate how to clean it. Mechanical filtration can be cleaned fairly thoroughly. Chemical filter components need to be replaced regularly for proper function. Biological filtration needs to be cleaned with old tank water and not until sparkling! 

Watch our video on how to properly clean your fish tank and media.

Combo Filters

These filters come with a combination of filtration types, usually sponges (mechanical/biological), carbon (chemical) and zeolite (chemical – ammonia scrubber). You do not have to use all of the components! Our office just uses the sponges; carbon is not necessary and an ammonia-scrubber isn’t needed for established, well-maintained systems.

Floss Cartridges

These are the most useless filters in the aquarium hobby. They are not meant to last and hemorrhage money. Switch them out for a sturdy sponge that you DO NOT need to replace every month. Only replace your filtration when it is about to fall apart.

Pressurized Filter

This is the most common type of filtration used on outdoor fish ponds. These units contain many small plastic beads used to house good bacteria for ammonia conversion. They need to be backwashed on a weekly basis to make sure the media is not compacted. Once compacted, these units need to be cracked open and cleaned.

To keep your fish happy and healthy, it is important that you do your maintenance regularly! Here’s a handy checklist to make sure you do everything on a regular basis: For Fish Tanks and For Koi Ponds


Top 10 Mistakes New Fish Owners Make – #7

The #7 Mistake – Feeding Your Fish Too Much

One of the more common “healthy” pet issues we see in all of veterinary medicine is obesity, and fish are no exception. They may have better control than your golden retriever, but overfeeding your fish can have more severe consequences than just rounder fish.

Unfortunately, there is no absolute calculation to tell you how much to feed your fish. It depends on their species, temperature, water quality, other stressors, the type of food, formulation and current disease processes. For cats and dogs, it all depends on body size and life stage. If you take any bag of cat or dog food and look at the back, it will tell you what life stage the food is intended for and what amount to feed for body weight. (This assumes that your pet is the correct weight for the body type and structure.) But when was the last time you weighed your pet fish? Fish should be fed based on body size, but we know this is an impossible task for most owners. Thankfully, fish are pretty good at determining when they are full. A bigger problem is what happens when there is too much food in the tank.

So what should I do to ensure my fish are not overfed? We recommend using the 5-Minute Method. It is very simple:

  1. Sprinkle a little bit of food into your tank. We recommend mixing it close to the filter return so all fish can get a fair share.
  2. When all the food is eaten, sprinkle a little bit more. If the food is not completely consumed, WAIT.
  3. Continue for 5 minutes or until the fish stop eating.

NOTE: Some species, like betta fish, are not great at regulating their intake. Keep in mind that their stomachs are about the same size as their eyeballs. Only a few pellets once or twice a day is adequate!

Why does this method work?

The biggest problem with overfeeding a fish tank is not just fat fish, but increased stress on your biological filtration. The breakdown of fish food, since it contains a lot of protein, causes an increase in the ammonia levels in your tank. Using this method makes sure that the food ends up in the fish, not the bottom of their tank. If you’re unfamiliar with ammonia and the nitrogen cycle, read this explanation.

For more information on fish food in general, watch our webinar.

New Tank Syndrome

New Tank Syndrome

When you set up a new fish tank for the first time, there are a few things you can expect to happen.

With a brand new filter, your nitrogen cycle has not been established. It will take 4-6 weeks MINIMUM to start cycling your new tank. There are countless products who claim they can instantly start your cycle, but they DO NOT WORK. We tested many products and only one was able to shorten our cycle by one week.

During those sensitive weeks, your tank will undergo the following spikes in ammonia, nitrite and finally, nitrate, as those bacteria colonies are established. You tank’s temperature and filtration capacity will determine how fast your cycle is established.

As your nitrogen cycle is established, your fish can be in danger of toxic levels of ammonia and nitrite. Therefore, it is essential to keep you bioload low in those first few weeks! Rather than fully stocking your tank from the get-go, start with only a few, hardy fish until your cycle is established. Keep a close eye on your parameters with a water quality test kit. Plot your readings and you will match the graph above.

Ammonia-binding products will prevent this cycle from occurring. Your tank will be stuck in perpetual “new tank” standing. We understand that it can be very scary to see your new tank spike with ammonia, but you cannot get to the end stage without the journey in between. Keep a close eye on your parameters and bioload low in the first 4-6 weeks and you’ll be all set from then on! If you’re really worried, or your fish start to act sickly, do a small water change to decrease the spike. And if you decide to replace your filter media every month, your tank will be continually cycling. So, ignore the box, and invest in a sturdy sponge instead.

Stop Replacing Your Filters!!

Dear Fish Tank Owners,

Please stop replacing your filter media every month.

I know it says to do so on the box! But, guess what? They do that in order to SELL MORE!!

When you take out your old filter media and toss it in the trash, you are discarding all of your good bacteria. These good bacteria maintain your biological filter and keep your nitrogen cycle up and running.

Most of those floss filter pads are designed to fall apart rapidly. Replace your filter media with a sturdy sponge (search “aquarium filter sponge”) and it will last you for several years! In order to keep them clean, squeeze them out gently in your waste water after siphoning your tank.

I know this goes against everything that is printed on the sides of your box of filter media pads, but you have to trust us. We are telling you this in the best interest of your fish and system. Just try it!


The Green Pea Myth

Constipated goldfish is the most widely over diagnosed case on the internet. There is not ONE peer-reviewed published paper about goldfish constipation and its treatments. Most commonly, goldfish “constipation” is misdiagnosed as a cure all for a sick fish. And in comes the main treatment… shelled green peas!

What is it about these tiny green globes of goodness that make most fish rise up from the almost dead?

One: They have almost no protein whatsoever, decreasing the amount of ammonia waste from your fish, decreasing the strain on your nitrogen cycle. Decreasing the ammonia waste from your system will make ANY fish better. Every 100 grams of green peas contains 5.4g of protein. Compare that to 100g of commercial fish flake and pellets having between 32-45g of protein.

Two: Green peas sink in water, therefore making fish dive to the bottom of their tank to eat, preventing excess air from ending up in their GI and swim bladder. Goldfish are physostomous, with a duct connecting their esophagus to their swim bladder. Considering the anatomy of some fancy goldfish varieties, these ducts are extremely short and therefore more air is able to get into the swim bladder, causing positive buoyancy issues. When fish eat at the surface, slurping food down like pigs, they can take in a lot of extra air. By feeding sinking peas, they don’t suck in as much air.

Three: Goldfish “indigestion” can be caused by an inappropriate diet. Goldfish, like all other carp, are omnivores, eating plants, bugs and almost anything tasty that fits in their mouths. In feeding them a flake or pelleted diet, you are aiming for a balanced diet. There are sooooo many fish foods out there, and a lot of them are based on educated guesses rather than actual research. As a fish owner, it is up to you to evaluate your fishes’ food to make sure it is appropriate. We have our most watched webinar on this very subject of reading fish food labels. Many of these “constipation” problems are from feeding very old food. After 6 months, your fish food has lost enough of the water-soluble vitamins, including vitamin C, that you are essentially feeding your fish cardboard. Getting a fresh bag of food, or switching the diet to our green peas (full of vitamins!), fixes almost all of the fish “indigestion” cases we see.

But what about all that fiber? 100g of peas contains 4.8g of fiber and most fish foods contain 3-5g of fiber, so it’s not really all that more fibrous.

All in all, peas are a low calorie treat that fish can enjoy. But are they magical, cure all tablets of greeny goodness? Sorry, but no.


The Nitrogen Cycle

The Nitrogen Cycle

As you may well know, water quality is a significant aspect of pet fish health. Like the air we breathe, the water a fish swims in is directly linked to their overall health. As a fish veterinarian, we routinely test the water our patients swim in for various parameters. We discussed pH and kH previous, so today, let’s look at the nitrogen cycle.

As you may notice, the traditional nitrobacter and nitrosomas bacteria species have been omitted from this diagram. This is due to the fact that there are just SO MANY different bacteria species involved in nitrogen-fixation, that we cannot simply define them in these two genuses.


In a fish tank, a fish’s primary waste is ammonia. Ammonia is produced by the breakdown of protein, the main staple of most fishes’ diets. Ammonia is excreted out through the urinary tract and gills. Ammonia is highly toxic to fish, causing death and increased secondary illness, so it is converted, through nitrogen-fixing bacteria, into nitrite. Now, nitrite can be just as bad as ammonia. Methemoglobinemia, or “Brown Blood Disease,” is caused by a build-up of nitrite. Nitrite can bind to hemoglobin in the blood and outcompete oxygen. This causes a brown coloration and the fish will asphyxiate from lack of oxygen. Thankfully, more nitrogen-fixing bacteria convert nitrite into the final nitrate. Nitrate is safe for fish at low levels, but at higher levels, and depending on the fish species’ tolerance, can cause the same issues as high ammonia. Nitrate is removed from the system by aquatic plants or water changes.

In established systems (over 2 months old with no new fish or equipment), your ammonia should be ZERO. Most low readings indicate your filtration capacity is inadequate or secondary to overfeeding. The highest reading acceptable on our test kit is 0.1 mg/L. The traditional API freshwater master test kit ranges between 0-0.25, so attaining a 0.1 reading will not occur. Due to the broad range of values, a 0.25 reading may be a false positive (reporting a higher value than what is actually present).


There are many commercial additives for removing ammonia from your tank prior to the nitrogen cycle. Some can cause ammonia test kits to read falsely high. These additives are short-term solutions that should only be used with significant health issues. They are not a long term maintenance solution. You MUST establish your biological filtration (good bacteria) for long-term fish health. If you have persistent ammonia in your tank, consider the following solutions:

  • Is your filtration adequate? Tanks with higher bioloads (size and number of fish) will require more than standard filtration. When in doubt, always filter more than you should.
  • Are you feeding appropriately? Remember, ammonia is produced from breakdown of protein in a fish’s diet. More food = more ammonia. Check your protein levels! For more information on fish diets, read this.
  • Are you doing lots of water changes? If you are constantly removing ammonia, your nitrogen-fixing bacteria will never become established.
  • Is there ammonia in your source water? Check the level coming out of your tap or well to make sure! You may need to consider another water source.

There are also commercial additives that will “quick start” your nitrogen cycle. Sorry folks, but these are a complete scam. With the exception of one product that slightly shortened the establishment of your nitrogen cycle, it will take 4-6 weeks MINIMUM to get your tank properly cycled. By “cycled,” we mean the establishment of a complete nitrogen cycle with ammonia being converted all the way to nitrate. We recommend starting with very few fish and monitor your ammonia, nitrite and nitrate levels carefully!

If you have any more questions about fish and nitrogen cycles, please comment below.


Top 5 Fish Mistakes – #2: Disorganized Cleaning

Top 5 Fish Mistakes – #2: Disorganized Cleaning

Top Fish Mistake #2: Disorganized Cleaning

How often do you clean your fish’s home? Do you have a regular schedule or do it whenever? No matter what kind of fish you have in either a tank or a pond, a routine cleaning regimen is essential to good fish health.

Go through the following checklist and see how much you do:

  • Clean filtration by backwashing sand or bead filter or rinsing or shaking matting or bio balls
  • Scrub the sides of the tank/pond
  • Clean the bottom of the pond using a vacuum or gravel siphon your tank
  • Water change through backwashing or siphoning
  • Check water chemistry using a drop-based test kit

If you’ve never heard of some or any of the above checklist items, now’s the time to start. Buy the equipment you need to get going and start with removing about 10% of the tank/pond water every other week. Get your kids or help or hire a maintenance service if you are unable or don’t want to clean it yourself. Purchase a test kit so you can follow your water chemistry as your system changes. Buy a test kit here.

Minimal or no system cleaning can lead to “Old Tank/Pond Syndrome.” In these cases, the water has sat around for so long that it’s eaten up all of its buffering capabilities, sending your pH crashing into the 6.0 range. Your fish are fine for now, since they’ve slowly adapted to the change and the low pH protects their gills from absorbing the toxic levels of ammonia wafting around your system. But I bet you’ve seen some low levels of chronic disease and death for the last few months? Don’t just go dumping a bunch of buffers or 100% water changes and expect your fish to survive! When correcting this problem, slow and steady water changes are what will get your fish through this problem alive.

If you do everything on our checklist, and on a regular basis, we are so thrilled to hear it! But did you know that you could be over cleaning your system if you do it too regularly or too thoroughly? Your filtration needs to have some layer of scum on it where those good bacteria can live and thrive. If you blast your filters until they’re pristine, you’re hitting the reset button on your whole filtration system. It’s the same as starting with a completely new system. It takes 4-6 weeks minimum for those good bacteria to start colonizing your filters. You can try quick start bacteria products, but we’ve tried them ourselves and seen no escape from that 4-6 week time frame.

Similar to not cleaning enough, over-cleaning can resemble “New Tank/Pond Syndrome.” In a system where bacteria have not been able to colonize or are never given the chance, you’re looking at a lot of ammonia and nothing else. No nitrite or nitrate will appear in your testing until those bacteria get to munching. In order to avoid this, try to avoid over cleaning with your trusty power washer and instead give your filtration a good shaking or very light rinse.

Here’s our friend, the Nitrogen Cycle, for reference.

Review your nitrogen cycle!
Review your nitrogen cycle!

Your maintenance regimen will vary with daily to weekly to monthly chores. Clean off floating debris daily and check your skimmer. Always check that your equipment is functioning properly. Make sure you have the contact information for a pond professional on hand to help with any emergencies. Follow our checklist for every two weeks to start, then start extending it by a week and keep an eye on your water chemistry. This will get you on the path for good water quality and happy fish!

Watch the complete FREE webinar here

No Pond Quick Start

Putting in a new pond comes with lots of challenges. You built it perfectly with great filtration and put in the most amazing fish, but your ammonia is off the charts and you can’t get your filter to start cycling. (Cycling is the process wherein good bacteria convert toxic ammonia to toxic nitrite to safe nitrate.) There are many products out there that claim they can “quick start” your pond and get it cycling faster. Well, we’re here to tell you that these quick fixes do not work.

After trying several products to get our own hospital tanks cycling, we were forced to wait not-so-patiently until they started cycling naturally. Most systems will start to cycle between 4-6 weeks, MINIMUM (temperature dependent). To prove this point, the first day we tested positive for any nitrite was EXACTLY 4 weeks to the day that we added fish to our tank. We added several different products to our 4 separate hospital tanks to try and speed this process up, but to no avail.

The only way to ensure a faster start is to take biologic media (mats, beads, etc) from a pre-existing, cycling system and add them to the new biological filter. Since we were starting from scratch across the board, this option was not open to us. Keep in mind: differences in water chemistry and temperature can cause changes in your bacteria colonies. Transferring established media to a pond with very different water chemistry and temperature variations will not do you any good and will kill the pre-established bacteria.

Sorry, but you’re just going to have to wait.

Review your nitrogen cycle!
Review your nitrogen cycle!

Do Fish Get Sick?

Do fish need a visit from the veterinarian? Absolutely YES! The responsibility with owning a pet doesn’t extend just to cats and dogs. If you are the proud owner of a fish, don’t you want to keep him/her happy and healthy? Since it’s hard to bring a fish to the vet for a checkup, we bring the vet to you! Aquatic Veterinary Services of Northern California was established to bring quality home care to your aquatic pets. And we don’t serve just fish! Aquatic turtles, amphibians and invertebrates are also our valued patients.

Fish and other aquatic animals get sick like any land animal. There are specific bacterial, protozoal and viral diseases that can affect them. Fish transmit diseases mainly through the water they swim in, which is why it is important to keep their water clean and healthy. Owning a fish is a lot of work, but no different than being responsible for a cat or dog. Cleaning a fish tank isn’t as big a deal as you may think and your fish will thank you for it!

How do fish act when they’re sick? Your fish won’t lie down and take a nap or cough when they’re feeling lousy. They may not swim around as much and just sit on the bottom of their tank. Or they may not be able to swim to the bottom or top of their tank. Some disease manifests as external spots of discoloration or open wounds. Fraying fins anywhere on the body is another sign to look for. Prominent or thick gills, sticking further out from the body wall, is a sign of gill disease or poor water quality. Sometimes a fish won’t look sick at all and just die unexpectedly. Remove any dead fish from the tank ASAP. If you think your fish is sick, or one ends up dead with no signs, it is important to check both the tank and your other fish for signs of disease.

How do you diagnose disease in fish? When a fish is sick, the first and most important place to check is its tank’s water quality. Poor water quality can cause fish to get sick more easily, because they are swimming in contaminated water. Stress occurs in fish, just like any animal by the production of the stress hormone, cortisol. The increased production of cortisol can decrease a fish’s natural immune system and make them more susceptible to disease. The most important water quality parameters to check are temperature, ammonia and dissolved oxygen. The temperature a fish likes can vary widely and it is important to know before you put a fish in its new tank. Cold water fish do not like tropical vacations. It is important to check your tank water temperature daily and make adjustments accordingly. Do not change the temperature on your fish tank if your fish is sick to “warm them up” or “cool them down.” Make adjustments ONLY to keep the temperature within the correct range for their species.

Ammonia is a natural waste product of fish and needs to be removed from the system by water changes. The nitrogen cycle is an important aspect of any fish tank. Bacteria in the water convert ammonia from fish waste to nitrite and nitrate. These need to be removed from the water or they can make your fish very sick. “Brown blood disease” or methemoglobinemia can be caused by too much nitrite in your fish’s water. Nitrite binds with the hemoglobin in your fish’s red blood cells and takes the place of oxygen, making it very hard for your fish to get enough oxygen in their system. A fish will end up suffocating no matter how much oxygen is in the system. A blood sample can confirm this, but if the tank water ammonia level is very high, it is a likely scenario.

Dissolved oxygen in the tank water is how your fish breathes. Fish need oxygen in their water in order to take it up in their gills. If your tank water is stagnant, fish may use up all their available oxygen and suffocate. It is important to have an air stone or bubbler in your tank and make sure your tank has a strong enough circulation pump to move all the water in the tank around.

There are other water quality parameters to look at, but these are the top three big ones to check.

Okay, so the water quality is okay, what’s next? If your tank water is okay, the next step is to perform basic diagnostics on a few fish from the tank. If any have died, it is important to perform a necropsy and look for any internal signs of disease. A necropsy is the fish equivalent of a human autopsy, and looks at causes of death. Live fish are anesthetized using a special, water-soluble chemical agent, and a skin scrape and gill clip are performed. A skin scrape is very simple and checks the external protective mucous of a fish. This barrier is the first line of defense for a fish’s immune system and is where many pathogens are trapped. Open wounds can also be checked by this method to look for signs of bacterial infection.

Gill clips may sound painful, but fish are anesthetized for this procedure and only a tiny, miniscule sample is taken. The fish may bleed for a few minutes post-procedure, but no adverse effects are seen. A lot of parasites like to hide in the gills because it gives them access to the nutrient-rich fish blood without having to enter the fish. Fish gills are a lot like human lungs. Humans can try to cough up pathogens, but this is not the case in fish. Both skin disease and gill disease can be treated through the water or oral medications.

So if the skin scrape and gill clip are inconclusive, what other diagnostics can you perform? There are many more diagnostic procedures that can be performed. If your fish is having problems swimming, floating or getting flipped upside down, a swim bladder infection may be to blame. A fish’s swim bladder helps it stay neutrally buoyant in the water column and not have to swim up and down all the time. If you’ve ever been SCUBA diving, the swim bladder is equivalent to a buoyancy compensation device (BCD). Bacteria and other pathogens can get into the swim bladder and make a nice, happy home. This is not nice for the fish, however. A needle can be inserted into the swim bladder and a sample of the bacteria removed. Appropriate antibiotics can then be prescribed to treat the infection.

Surgery can also be performed on fish! You may think that all surgery is performed in dry environments, but fish can be anesthetized and surgically operated on as well! A chemical agent is dissolved in water that can be circulated over the fish’s gills using a regular tank circulation pump. They are kept moist by sitting on a foam pad soaked in water. Sometimes surgery is simple. If a fish swallowed a rock from the bottom of its tank, a simple pair of forceps can reach in and pull it out. Other times, say a fish with a cancerous tumor, surgery is not so simple. Fancy goldfish, the ones with the bubbles on their head, need regular procedures to make sure they can see. Surgery is very similar to procedures performed on a dog or cat, just on a smaller scale.

In conclusion, fish are just as susceptible to disease as any other animal. It is important to prevent disease as best you can by keeping their water clean. If you have the space to quarantine new fish, this may save you some trouble if a new fish brings new disease into your tank. Any additional questions, please e-mail