Top 10 Aquarium Myths In Fish Keeping

The saltwater aquarium world is filled with myths and misconceptions passed down from reef hobbyists to reef hobbyists. Whether you are a newbie reef keeper or an expert hobbyist with years of experience under your belt, you’ve probably come across a few common aquarium myths. 

Let’s dive right in!

1. Fish Grow To The Size Of Their Reef Tank

This is one of the most damaging myths about the reef aquarium hobby. If this ‘fact’ were true, I would have a great white shark-sized fish swimming in my living room display tank. 

The truth… fish don’t just change their growth and size to match their environment - we only have to go snorkeling or diving in the ocean to see a wide range of fish sizes! What is reality is that in aquariums that are too small, fish’s growth can become stunted due to stress, poor water conditions, and the build-up of growth-inhibiting hormones. This stunted growth causes many issues such as weakened immune systems, deformities, and much shorter lifespans. 

Another reason this myth exists is that some hobbyists (more common in new hobbyists) do not realize they are purchasing juvenile fish. For example, most clown triggers and Naso tangs are sold in their juvenile stage. People see these fish and fall in love (I mean, who can blame them) and take them home without consideration of their adult size. 

Before purchasing fish, always research the potential adult size and check that your aquarium can accommodate them for their entire lifespan. 

2. Marine Tanks Only Need 1-2 Days To Settle Before Adding Fish

The first time setting up a reef aquarium is extremely exciting, and waiting for the aquarium to cycle can be challenging. Sadly, many fish stores perpetuate the myth that you can start adding fish to an aquarium after only 24-48 hours of running your system. This poor advice, unfortunately, leads to countless failed tank systems and unnecessary fish deaths. 

The truth is, establishing the nitrogen cycle in a new reef tank takes much longer than a couple of days, usually 4-8 weeks at a bare minimum.

During this time, beneficial bacterial colonies will develop in your filtration system, within the substrate, and on any live rock. These bacteria are a hobbyist's best friend - they play a key role in breaking down toxic ammonia and nitrite into less harmful nitrate. 

So, for new reefers, be patient! Remember to test the water parameters with a water test kit before considering adding any livestock. While we don’t advocate for speeding things along, there are several ways to speed up the cycling process in aquariums. 

3. Cleaning fish & Invertebrates Will Clean Your Tank For You

Ever been told “Throw in a couple of emerald crabs and your algae problem will be fixed,” or “Did you know that cleaner wrasse will keep your fish parasite free”? Both of these are great recommendations, but they are not cures and have oversimplified the reality. 

While there are many algae-eating reef fish and invertebrates like snails and hermit crabs that do consume detritus and algae in aquariums, they are not replacements for proper reef tank maintenance. Also, they are live organisms too, so they also produce waste, adding to your aquarium’s bioload. 

Plus, many algae-eating fish that are considered “cleaner” species have specific dietary requirements that are challenging for new reef hobbyists. For example, mandarin dragonets are often sold in fish stores as algae eaters, but they are extremely challenging fish to keep. 

The cornerstones of a healthy marine environment come down to regular water changes, maintenance, and proper filtration. Think of aquarium clean-up crews as handy assistants rather than aquarium maintenance replacements. 

4. Fish Have A Short Memory Span

Any hobbyist who’s kept fish knows this is completely false. Just look at how quickly a fish recognizes you as the food provider when you walk up to the tank - fish are quick to gather in front of the tank! 

This common aquarium myth and misconception is where the saying “memory like a goldfish” came from. Scientific research has shown that fish have impressive cognitive abilities and long-term memory. Fish can recognize human interactions, remembering training exercises for months, sometimes years, navigate complex environments, and even learn from observing other fish. 

In particular, marine fish display social behaviours and impressive memory capabilities! So, next time someone says your fish is simple-minded with a three-second memory, you can confidently correct their outdated comment. 

5. Marine Aquariums Salt is the same as sodium chloride

Regular aquarium salt that's sold for freshwater aquariums is indeed primarily sodium chloride, however, marine salt mixes contain far more complex formulations that contain dozens of elements to replicate natural seawater. 

Marine aquarium salts have perfectly balanced levels of magnesium, calcium, strontium, potassium, and many trace elements to ensure the health of fish, corals, and invertebrates. Using household salt or basic aquarium salt can cause serious health problems for your livestock. 

If you are unsure what salt mix is best, take a read of our article HERE!

6. The More Filtration, The Better!

While adequate filtration is key to a successful aquarium, there is a persistent aquarium myth that you can’t have too much filtration. This is incorrect, and too much filtration can be problematic, particularly in reef tanks:

• It can increase stress.

• Protein skimmers may remove beneficial bacteria along with waste products

• Too much chemical filtration can strip the water of trace elements and organic compounds that corals need

Always aim for filtration that is appropriate for your specific aquarium system and bioload - read more HERE. 

7. A Smaller Tank Is Easier For Beginners

Many newbie hobbyists are advised to start with a “manageable” pico or nano reef tank. While it may seem logical to start with a smaller tank vs a larger aquarium, it contradicts the fundamental principles of water chemistry. 

Smaller water volumes are much less stable and forgiving, which can quickly cause dangerous parameter swings. For beginners, we recommend a medium-sized tank. This will offer you a better learning experience with more room for error and stable parameters. 

8. Fish Can’t Feel Pain

This very outdated belief has sadly led to poor handling and inadequate care. Research has shown that fish do feel pain, although it is different from how we do. 

Fish have peripheral nociceptors (pain receptors) that release pain-mitigating hormones when they become injured, and as a result, fish display behavioral changes consistent with a pain response. 

When handling or transferring fish to a new tank, use proper nets and containers to minimize injuries and stress. 

9. Aquarium Accessories Are Just Marketing Gimmicks

While it is true that not every aquarium gadget marketed to hobbyists is necessary, the core aquarium equipment serves vital functions. This includes proper lighting, protein skimmers, pumps, etc. 

Cutting corners on essential aquarium equipment typically leads to water quality issues, increased stress, and more expenses from problems. 

10. Large Water Changes Remove All Beneficial Bacteria

This misconception has stopped many hobbyists from maintaining proper water quality. The truth is, beneficial bacteria primarily live on surfaces, not in the water column itself. 

Regular water changes, even larger ones (they are sometimes needed), will not massively impact your biological filtration. 

Conclusion

As marine hobbyists, we are constantly learning and understanding the complex ecosystems of saltwater aquariums. By learning the common aquarium myths, you can make informed decisions and provide the best care for your system. 

If you have any questions about setting up or maintaining your reef aquarium, contact the Reefco Aquariums team today!