Fin-tastic Tank Ideas For Small, Medium & Large Sized Fish Tanks

Since childhood, as a hardcore aquarist, I have always fancied having a gigantic aquarium. But I had to start with smaller ones due to space and other issues, like many others. 

However, that gave me the scope to explore all sizes of fish tanks, and now I have enough experience to suggest you some of the coolest aquarium ideas of different capacities. Whether you want a freshwater tank or a saline one, this list will give you ideas to play with. 

As a bonus, I will also give you tips on the type of fish suitable for different tank sizes and how to clean and maintain them. So, keep on reading!

Most Creative Small to Medium Fish Tank Ideas: 2.5 to 45 Gallons

If you don’t want a common goldfish, try out these beginner-friendly breeds that are perfect for small aquariums. 

  • Guppies
  • Zebrafish (Zebra danio)
  • Neon Tetra
  • White Cloud Mountain Minnow
  • Mickey Mouse Platy
  • Dwarf Gourami
  • Chili Rasbora
  • Bolivian Cichlids
  • Barbs
  • Betta

The Rocky Tank

Decorating small tanks can be tricky as it is very easy to go overboard. If you want a minimal and easy-to-maintain look, you can add different sizes of pebbles and riverbed stones over a thin substrate layer. 

This setup is perfect for freshwater fish. Place the rocks in a way that fish can have some hiding spots. They are the safe spaces fishes look for when feeling stressed, frightened, or uncomfortable. 

The Tentacle Tank

The Tentacle Tank

If you want to add fun and creativity to your mini fish tank, then this idea takes the cake. I found this amazing idea on Reddit where another aquarium enthusiast custom-printed octopus tentacles and placed them in his betta fish tank. 

The tentacles were made of aquarium-safe plastic so that they don’t leach over time. You can paint them with acrylic paints and then coat them with a clear water-based finish or fish-safe epoxy. Leave them for at least a week and a half before putting them in water. 

And for those who are wondering about the plant, it is a ball of Anubis, which is a great hiding spot for a betta. 

Crystal Cave-Inspired Tank

Crystal Cave-Inspired Tank

The oceans are full of wonders, and gigantic underwater crystal caves are one of them. This one right here is a 5-gallon nano fish tank made for Lampeye Killifish and Cherry Shrimps, but you can switch them with Blind Cave Tetras and gold spotted shrimps as well. 

Since it was for killifish, they used freshwater with a pH of 6-7. For the crystal cave, you can use rocks and crystals. For crystals, you can use any variety of quartz (since they are the most stable crystal and don’t decay easily).

Tips for beginners: Never put coral skeletons in a freshwater tank. The calcium leeches over time due to freshwater’s pH, making it more basic than it should be. It can be threatening for your fish. 

Tea Table Tank

tea table tank

If you are looking for home decor that your guests will remember for quite some time, then a tea table fish tank is all you need. They come in different shapes and sizes, but irrespective, each one of them looks majestic. 

Depending on the shape and size of your table, you can increase or decrease the number of aquatic plants and fish you want to keep in it. 

If you can’t get your hands on a ready-made table aquarium, you can DIY it by following this video. However, you can also get tons of other inspirations on Pinterest that don’t require much work and can be easily made by altering your existing medium-sized tank. 

Large Fish Tank Ideas That Are Simply Jaw Dropping: 50 to 300 Gallons

Even though technically you can keep any choice of fish in a large fish tank, some breeds require more space (at least 50 gallons) and look exceptionally good in larger tanks. 

  • Freshwater Angelfish
  • Oscars
  • Silver Dollar
  • Juvenile Bala Shark 
  • Fancy goldfish 

The Finding Nemo Tank

finding nemo tank

Since the release of the Disney blockbuster “Finding Nemo” and its sequel, many aquatic hobbyists have tried to make miniature versions of it. If you or your kid is a Nemo fan, it indeed will be a surprise for them.

To make a Nemo and Dory-inspired tank, you only need a 55-gallon saltwater tank with some corals. If you already don’t know the fish’s names, they were clown fish (Nemo and his father) and blue tang (Dory). 

Clownfish and Tangs are from similar habitats, and a reef tank is perfect for them. Moreover, both are very safe to keep together. Clownfish love different Anemones like Bubble Tip, Leather Sea, Aurora (Beaded Sea), and Corkscrew Sea. And for corals, you can go for Duncan or Hammer corals. 

Here’s a video tutorial showing how to make a dreamy shallow reef tank at home. 

Pro Tip For Maintaining Reef Tanks:

Remove and replace 10% of your tank water on a weekly basis to maintain the aquarium water quality and use only high-quality salt. When mixing fresh saltwater, ensure it is properly heated to the tank’s existing temperature. 

Keep a weekly check of temperature, pH, and salinity, too, since coral reefs are very sensitive to these parameters. 

Planted Rainbowfish Tank

planted rainbow fish tank

If you have the space to accumulate a 220-gallon tank, you must try a planted rainbowfish tank for once. The multicolor fishes look gorgeous with the leafy green plants and are very easy to maintain. 

Planted fish tanks are great for boesemani rainbowfish as they replicate beautiful underwater enviournement that are naturally occurring. So the plants and fish get to establish a healthy and complementary relationship. 

The fish provide carbon dioxide and nutrients for the plants, and in exchange, the plants supply biological filtration and oxygen to the water. Hence, in the end, your job gets easier as you don’t need to do frequent maintenance. 

Here’s a video of an experienced hobbyist setting up his planted rainbow fish tank. Give it a watch if you are looking for some inspiration. 

Things to remember:

  • Use a high-quality mineral-rich plant substrate and set up the pants for at least 2 to 3 weeks before adding the fish. 
  • Having multiple male rainbowfish in one tank can cause aggressiveness, especially before breeding season. So limit to only one male fish per tank. 

Biotope Tanks

biotope tank

Biotope tanks are very popular due to their ease of maintenance. The concept of this tank is that whatever fish, plant, or invertebrate you put in the aquarium has to be from a similar habitat. 

The aim of this tank is to mimic a naturally occurring environment. So basically, you will be building a little ecosystem!  So you need to carefully study the environment you are trying to mimic and pick plants and fish that are native to it. 

Here’s a detailed guide on how to set up different biotope tanks that mimic different parts of the globe. 

Worst Fish Tank Ideas You Must Avoid 

If you are a genuine aquarist, you would never sacrifice the health of your finned friends over aesthetics. No matter how cute and visually appealing these tanks look, they are extremely detrimental to your fish’s health. So make sure you avoid them. 

  1. Mason jars/ cylindrical jars
mason jars
cylindrical jars

2. Fish bowls

fish bowls

3. Glass Vases/ Bottles

glass vases

4. Aquaponic setups

Aquaponic setups

After looking at the images, the general similarity you can draw is the space crunch.  One fact that every seasoned aquarist can vouch for is the bigger the space, the better it is for the fish. 

Small containers like the ones shown above massively restrict oxygen levels. They have very little surface area for air-water interaction, plus the rounded edges can also impact the vision of your fish. Hence, by choosing a bottle, you’ll be making things even worse. 

It can be hard to digest as fish bowls once were marketed as the prime choice if you plan to keep a single fish, but over time experts have discovered issues with the setup. 

Small vessels like fish bowls and vases have

  • Inconsistent temperature
  • Lack of oxygen and ventilation
  • Poor nitrogen cycling
  • Drastic pH swings
  • Restricted swimming space

All these combined will only make your pet sad and unhealthy over time, so if you cannot manage at least a 2.5-gallon tank, you should reconsider your decision to keep a fish. 

Cleaning Tips For First-Time Aquarium Owners 

No matter how fancy or simple you decide to keep your fish tank, cleaning it will be a must. Hence, here are assorted tips you can follow in cleaning your freshwater and saltwater fish tank. 

For Cleaning Fresh Water Fish Tank:

  1. Do partial water change every two weeks to avoid the buildup of fish waste, uneaten food, and other debris. Taking out 20-30% is ideal, depending on how many fish and aquatic plants you have. 
  2. To clean the gravel and pebbles at the bottom, use a siphon. 
  3. Use algae scrapers to scrape off algae buildups. Opt for a magnet cleaner if you have a large tank and can’t reach the corners with the scraper. 
  4. Maintaining the filter is the most crucial part of having fresh and good-quality water, so clean/ change it periodically. 
  5. Remember to clean the equipment (heaters, pumps) every time you deep clean the tank. Or else they can become the source of algae and bacteria buildup. 

For Cleaning Salt Water Fish Tank:

Apart from the algae and gravel cleaning, follow these two tips to care for your saline water fish tank. 

  1. Invest in a good protein skimmer as it helps to maintain the water quality in a saltwater tank by removing excess organic matter.
  2. Do a water replacement every fortnight to maintain the nitrate levels. Taking out 10% water and replacing it with fresh saltwater will do the job. 

For Cleaning Planted Tanks:

Cleaning your planted tank for the first time can be overwhelming. So to make it easier, follow these simple tips.

  1. Be very gentle while taking the plant to avoid uprooting it. As a temporary pad, you can place them in a wet paper towel (for a very short period) or a bucket filled with aquarium water (for a longer period). You can also use aquatic pant bags if you need to travel with them. 
  2. Avoid chemical cleaners to clean your tank, as they can damage the plants. 
  3. Trim the plants if they look unhealthy and have too many dead and damaged leaves. 
  4. If the plants have algae and debris buildup, clean them with a soft bristle brush or damp cloth. Do not use chemicals or detergents. 
  5. When replanting, make sure the thickness of the substrate is the same as it was before. 


How can I make my fish tank more interesting?

Lighting and props can drastically change the look of your fish tank. Lights also help promote the health of your fish and aquatic plants. You can choose from different LED lights, fluorescent lights, full-spectrum lights, and metal halide lights depending on your size and type of fish/ plants. 

What fish live best together in a tank?

Some of the most compatible fish breeds include Neon Tetras and Corydoras Catfish, Guppies and Platies, Angelfish and Tetras, Mollies and Swordtails, or Gouramis and Rasboras. 

What fish can I keep in a 40-gallon tank?

A 40-gallon tank is a medium size fish tank and can accommodate a variety of fish. However, ensure that you are only keeping the compatible breeds together. In a 40-gallon tank, you can keep Neon Tetras, Cherry Barb, Dwarf Gouramis, Guppies, Swordtails, and Corydoras Catfish. 

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