Photo by kazuend on Unsplash.

Bare Bottom Tank: Pros, Cons, Usages

Bare bottom tanks are a divisive topic in the fishkeeping world. Maybe their polarizing power stems from their looks or maybe many hobbyists associate them with fish stores, where numerous fishes are crammed together in glass tanks with barely any decorations.

It isn’t a particularly pleasant sight but fish stores often opt for bare-bottom tanks because they have several crucial advantages over tanks with substrate.

Bare-bottom tank pros:

  • Bare bottom tanks are straightforward to clean.
  • No substrate means no waste accumulation.
  • It’s also cheaper, as substrates cost money or DIY effort.
  • There are no invisible active agents like bacteria living in the substrate which makes the water parameters considerably easier to control.
  • Since the water parameters are more stable, bare bottom aquariums are excellent for breeding tanks, hospital tanks, or quarantine tanks.
  • Bare bottom tanks provide more swimming space, both horizontally and vertically (as substrates usually take a few inches) if there aren’t any decorations.
  • No decorations mean better water circulation.
  • The lack of decor also allows for a good view of the fish, as nothing obstructs the sight and there are no hiding places.
  • The lack of decorations also removes the risk of fish hurting themselves against sharper edges.
  • Bare bottom tanks are arguably the best choice for minimalist setups.

Now, the last few are great in the context of selling and buying fish. Good visibility helps mightily in choosing the fish you want.

But at home? Really?

Don’t they look ugly?

Here are the main cons of a bare bottom tank:

  • Tanks without substrate lose some aesthetic appeal. But bare bottoms can be perked up with a minimalist decoration or two. Perhaps a tiny underwater biodome where a squirrel lives.
  • No substrate means a very limited bacteria population. Bacteria in fish tanks can be extremely helpful in filtering ammonia.
  • No-substrate tanks require regular cleaning and/or more powerful mechanical filtration to keep things in healthy shape.
  • Certain fish and invertebrates need sand or gravel to thrive.
  • Bare bottom eliminates or severely limits the possibility of growing plants. Aquarium arboretums are awesome

These are the main pros and cons of bare bottom fish tanks. Let’s break them down now.

The Advantages of Bare Bottom Tanks

Is it OK to have no gravel or sand in a fish tank?

Totally. Many fish can thrive in a bare bottom tank.

Here’s why.

Bare Bottom Tanks Have More Stable Water Chemistry

Substrates are great for filtering water, but getting them to do that isn’t as straightforward as it sounds.

Inert substrates like gravel or sand need time to establish healthy colonies of beneficial bacteria that break down waste. Then, if you put antibiotics in the water column to heal a sick fish or two, the bacteria will take a hit that can lead to water imbalances and ammonia spikes.

Active substrates like topsoil or specialized aqua soil alter the water chemistry a lot and require regular water changes, especially early on.

By removing the substrate layer from the equation, bare bottom setups allow fishkeepers to maintain the desired water conditions with relative ease. All the waste stays at the glass bottom, in plain sight, and is super easy to clean with a hose or siphon.

That ease of maintenance and stable water chemistry makes bare bottom tanks the best choice for:

  • Breeding fish (some decorations help though)
  • Quarantine tanks
  • Hospital tanks
  • Tanks for difficult species — Fish species that prefer very specific conditions and suffer tremendously at the slightest change are best kept in bare bottom aquariums.

Bare Bottom Tanks Provide a Lot More Space

No or minimal decorations and no substrate free up the entire tank. Compared to a moderately scaped aquarium, that’s could mean a lot of free real estate. Bare bottom tank is certainly one way to go if a fish grows confined by its current aquarium and obtaining a new one is not an option. Fishkeeping isn’t a very expensive hobby, but starting a new, larger tank still requires investment and, often a limiting factor, space in the house.

What’s more, having a box of glass and nothing else allows you to enjoy its inhabitants every time you look at the aquarium. They will be swimming around happily, enjoying freedom of movement.

Better Water Circulation

It’s often said that bare bottom aquariums require more cleaning because substrates absorb debris and waste. To an extent, that’s true. Biowaste fallen on the glass bottom just stays there, decaying and looking messy.

But if you get yourself a powerful filter, this becomes a non-issue. A strong filter that is not obstructed by hardscape elements can provide superb water circulation and take care of nearly all the waste.

Indeed, a good filter will likely make up the difference in price. You’ll save some cash if you don’t buy substrates, but good filters don’t come cheap either. Two smaller ones could work as well. Coincidentally, a secondary filter in the tank will provide redundancy and a surface for beneficial bacteria to dwell upon.

Bare Bottom Tanks Are Safer for Fish

Aquariums with no substrate and decorations are safer for fish in two ways.

First, as discussed, substrate, plants, and certain hardscape elements can affect water conditions in unpredictable ways.

It is easier to keep steady water parameters in a box that contains only water.

Second, more pertinent to hard decorations, fish can damage themselves against driftwood or volcanic rock. If startled, especially at night, large or medium fish could crash against a sharper protrusion, damaging a fin or worse. The risk is low but existent.

Now, a glued silk plant or a rounded driftwood are safe choices that could add an accent to the tank.

Ceramics can serve as caves.

Besides adding visually striking elements to the minimalist look of a bare bottom tank, safe decorations provide an important utility, too. Fish can scratch against them to telegraph discomfort that must be addressed.

Bare Bottom Tanks Are Excellent for Goldfish

Tanks that are easy to keep clean are great for goldfish. They produce a lot of waste. So much that you could use it on your house plants, if you fancy, to fertilize them.

The reason why goldfish produce so much waste lies in their large intestines. But it is not their sheer size. It is the fact that goldfish have only intestines and nothing else. There is no stomach to properly digest food and lots of it goes out of the fish.

In large, the lack of stomach dictates the goldfish diet. Goldfish should eat food they can process through their mouth, pharyngeal teeth, and extended intestinal tract. 

Fascinating fancy fish they are!

Strong filtration with good water flow will remove most of the waste. Of course, good filtration can help you keep goldfish in substrate, with adequate decorations, too.

Are Bare Bottom Tanks Bad?

Bare bottom tanks are not suitable for certain species. Loaches, corydoras, and some loricarias like sand.

But many species don’t care whether they swim above sand, gravel, pebbles, or glass. For them, bare bottom tanks are not bad. If kept with adequate filtration and maintenance, they can be home for many, for a long time.

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