Top 10 Beginner Aquarium Mistakes – (We’ve All Done Them)

Don’t worry, we’ve all been there! We were all new guys once and we all made plenty of beginner aquarium mistakes, myself included! But why start from scratch and repeat the same mistakes we’ve all already made? Let’s get proactive!

Top 10 Beginner Aquarium Mistakes

1 – Adding Fish To An Uncycled Tank

I know you’ve heard it before from your local fish store guys and it just doesn’t make sense to you. It’s very natural to want to buy a fish, setup your tank, and throw it in immediately. You just want your tank set up already.

But its true, you can’t add fish to an uncycled tank. You must allow your tank time to cycle. Adding fish to an uncycled tank will cause an ammonia spike.

You’re going to end up killing those fish and have to start all over again. You’ll wonder what went wrong and you may even talk yourself out of the hobby.

So do more research , watch plenty of videos on YouTube, watch some of my videos, here’s a great one on the nitrogen cycle.

But it is 100% accurate that a fish tank needs to be cycled to sustain life in your tank.

With that being said, there are ways to instantly cycle your tank with fish in at the same time. Understanding the process is important to ensure the safety of your fish. But this method is the fastest way to get going with your hobby. Read More Here.

2 – Not using de-chlorinator or water conditioner when water changing

I know this is very obvious to some, but many beginners don’t know about de-chlorinating their tap water.

When you do a water change, your tap water has chlorine in it. Chlorine is going to kill every living thing in your tank. It’ll kill bacteria, kill your fish, kill your plants.

Chlorine is a bad thing and we must de-chlorinate our water using Seachem Prime, Api stress coat or any of the other many water conditioners on the market, use which ever you prefer.  But you must dechlorinate new tap water in your tank.

3 – Too Much Light In Aquarium

You may be surprised to find out that the light in your aquarium is not necessary for your fish. That light is totally for you. It’s so that you can view your fish, watch them and enjoy them but it has no benefit for your fish.

Too much light can actually cause stress for your fish. Too much light may even cause aggression problems because they can see each other so well it may promote fighting and some fish may attack each other more often.

Too much light may cause algae growth in your tank which will cause a cloudy, dirty looking tank.

Live plants do require light but the fish themselves do not. Your living spaces natural light source is more than enough. A general rule of thumb in the aquarium hobby is that you want your light on about 8 hours or less if possible.

4 – Overfeeding Fish In An Aquarium

Now I’ve said this before and I’ll say it again. If you’re new to the hobby, you’re most likely over feeding. Cut it in half…Yes, half.

Over feeding leads to over eating, over eating leads to more poop, more poop leads to more nitrates, more nitrates in your tank are going to cause your fish to stress out which is going to weaken their immune system leaving them susceptible to disease, parasites, and bacteria. This isn’t going to be good for anybody.

Also, there are always parasites and bacteria present in my tank and yours, right now.  The only thing fighting them off is your fish immune systems. Which is why it’s so important not to stress your fish out.

The less stressed they are the stronger their immune system is to fight off disease, bacteria, and parasites. If none of that made sense to you about over feeding here’s something that will…over feeding will cause ugly, cloudy, dirty looking water. So don’t do it.

5 – Water Changes And Filter Cleanings On Same Day

This is going to disrupt too much of your beneficial bacteria at the same time.

Even though there isn’t any beneficial bacteria in your water column. When you have a new immature tank trying to cycle and establish itself you don’t want to disturb to much all at the same time.

Instead what you want to do is alternate between water changes and filter cleanings. If you do water changes every 2 weeks then clean your filters the week in between. If you water change weekly then clean your filter somewhere in the middle of the week.

Disrupting too much beneficial bacteria at the same time will cause an ammonia spike and a bunch of other problems in your tank.

6 – Cleaning Bio-Media With Tap Water

For the same reason as earlier stated the chlorine in your tap water will kill all the beneficial bacteria on your bio media. This will cause an ammonia spike in your tank and you’ll have a bunch of dead fish.

Preferably you want to clean your bio-media with TANK water. Just a quick rinse in tank water is all that’s necessary.

There is no need to ever replace your bio media. Bio-Media is good for many many years to come. Here’s a helpful video on cleaning a canister filter with bio-media.

Glad you stuck around past the first 6 beginner aquarium mistakes. Those were the most basic for the very new. Now we’re going to get into some mistakes that even some veterans are making right now, including myself. I’ve had to learn them the hard way and I’d like you to avoid the same fate.

7 – Oxygenation And Surface Agitation

I know it may be easy to just buy a bubbler or an air stone, throw it in the tank and think that should be good enough. That may be the case initially.

With time we’re going to add more fish which will reduce the oxygen.  More fish will add more nitrates to the tank, which will reduce more oxygen.

Your fish are also going to grow, requiring more oxygen.

The best bet is to get a good wave maker. A wave maker pointed up at the surface of your tank is going to create a wave all the way across the surface and give you great surface agitation. This will make sure you always have a well oxygenated tank. Here’s a great video on wave makers.

8 – No Backup for Oxygen

Oxygen is so important that you need to make sure you back it up in case there’s a power failure. The livelihood of your fish in an aquarium is relying on power.

If you ever lose power you’ll lose everything in your tank. Including filters and heaters. But the first thing that will kill your fish is a lack of oxygen.

So you should have a battery backup that monitors your power source and in the event that you lose power the backup kicks in an supplies oxygen to your tank until the situation can be rectified.

9 – Inadequate Heating Safety

I’ve heard many horror stories of coming home form work and finding all your fish have jumped out of the tank and they’re spread across the floor because your heater failed and stayed stuck in the on position and basically cooked them.

Having a failsafe system as a backup for your heater in case it stays stuck on or doesn’t turn on at all is very important.

With a redundant heating system 2 heaters compliment each other. If one fails to heat the other carries the load until it can be fixed.

A redundant heating system plus a temperature controller is even safer. In the circumstance where a heater stays stuck in the on position a temperature controller will ensure power is removed from a faulty heater and prevent the tank from over heating.

10 – Not Using A Quarantine Tank

Come on guys, we have to quarantine our fish!

Fish disease is rampant. Wherever  you get your fish from, via the local fish store or you order them online and they got shipped to you, your fish are going to be stressed out from the transport.

As stated earlier stress is going to weaken their immune system and they can catch many diseases that are very contagious. If you put a sick fish in your main tank with your main fish it’s very likely that whatever they have will spread to everybody. In this case you’ll need to medicate the whole tank which can be very costly.

You can easily lose fish and even and entire tank by not being able to control some parasite that has spread to everyone in the tank. It’s possible to not even notice it and you catch it too late. very easy to lose an entire tank.

I highly suggest you always quarantine new fish. Ensure they’re ok, medicate if you have to, watch them for a couple of weeks, and make sure they’re eating well before attempting to add to your main tank.

Because when they are added, everyone’s going to be very excited to meet your new guys!

Bonus Tips for beginners in the Aquarium Hobby

Don’t buy an itty bitty tiny little tank. A small tank is actually going to be harder to maintain because you’ll have big fluctuations in water parameters. It’ll drive you nuts!

It’s harder to keep PH the same, harder to keep the temperature right, harder to test for ammonia and nitrates in a smaller volume of water.

It’s easier for parameters to fluctuate in a smaller volume and this can be deadly to new fish with a new owner. This can also easily lead you to regret your decision to enter the hobby and leave it all together.

I suggest you start with a bigger tank. A simple and easy way to justify a bigger purchase is to buy it used, second hand.

On Craigslist or Letgo or any of those apps where people sell their used stuff you can get a nice sized 30-50 gallon tank to start with at a very good price. You could easily find something that comes with the whole set as well.

A tank that comes with the stand, the filters, and the heater. Buy something complete that way it’ll be easier to set up and get going.

If you feel that maybe the hobby isn’t for you because it does require a lot of work, it’s not for the lazy, ask anybody, you can easily resell it right back on the same platforms you bought it from and take a very minimal hit on the loss.

So no harm no foul. You were able to get in an try it out, and if it doesn’t work out someone else will gladly take that second hand tank of your hands.