Bottom Dwellers Fish

Bottom dweller fish play an important role in freshwater and saltwater aquarium ecosystems. These fish inhabit the lower levels of the tank, often sifting through the substrate in search of food. While the term “bottom dwellers” refers to their vertical orientation in the tank, it also hints at their behavioral tendencies. Understanding bottom dwellers’ types, behaviors, proper care, and misconceptions can help aquarists pick the right fish for their setup.

What Are Bottom Dwellers?

Bottom dweller fish spend most of their time near the bottom of the aquarium or body of water. Most species are omnivores or scavengers, feeding on food particles in the substrate, aufwuchs growing on decorations, or tiny invertebrates. Their location on the lower half of the tank allows them access to fallen food and debris.

The bottom dweller designation refers primarily to their position in the tank, but many exhibit additional characteristics suited to their lifestyle:

  • Flattened bodies to hug the bottom while resting or swimming
  • Sensory barbels to locate food
  • Small, sucker-like mouths to vacuum or graze on surfaces
  • Downward facing eyes to spot food below
  • Camouflage coloration to blend into the substrate

Unlike other aquarium fish that swim freely throughout all levels, bottom dwellers stake their claim on the lower regions. They serve as the clean-up crew, consuming uneaten foods and helping break down waste.

Types of Bottom Dwellers

Bottom dwellers come in all shapes and sizes, ranging from tiny shrimp to large plecos. While they occupy the same tank area, their behaviors and care needs vary.

Bottom Dwelling Fish Freshwater

Many freshwater bottom feeders thrive in home aquariums. Common choices include:

  • Corydoras Catfish: Armored catfish with sensory barbels. Peaceful schooling fish.
  • Loaches: Eel-like body shape. Most are peaceful but can be territorial towards their kind. Need groups.
  • Plecostomus: Large armored catfish. Help clean algae but produce lots of waste.
  • Gobies: Small, peaceful fish that sift through substrate. May jump from tank.
  • Snail Eating Loaches: Loaches that consume nuisance snails. Require meaty foods too.

Bottom Dwelling Fish Ocean

Saltwater tanks also have options when it comes to bottom dwellers:

  • Blennies: Algae eating fish with scaleless skin and elongated bodies. Peaceful but territorial.
  • Gobies: Typically smaller bottom fish that feed on invertebrates. May jump from tank.
  • Dragonets: Beautiful small fish that eat copepods and other zooplankton. Require stable parameters.
  • Flatfish: Flounders, soles, and tonguefish. Uncommon but unique additions. Prone to jumping.

The main difference from freshwater species is their need for stable water parameters. Saltwater fish are more sensitive to fluctuations in water conditions. Providing stable pH, salinity, and temperature is crucial.

Bottom Dweller Fish Examples

To showcase their diversity, here are some specific examples of bottom dwelling fish:

  • Yoyo Loach: Peaceful schooling loaches with a pale body and dark band across the eyes. Max size around 2.5 inches.
  • Kuhli Loach: Eel-like loaches with horizontal black stripes. Hide during the day. Max 4 inches.
  • Bristlenose Pleco: Armored catfish reach up to 5 inches long. Help clean algae from surfaces.
  • Panda Cory: Iconic black and white cory catfish. Peaceful community fish that schools.
  • Spotted Mandarinfish: Stunning saltwater species with blue, green, and orange coloration. Feed on copepods.
  • Pink Streaked Wrasse: Reef safe wrasse with vibrant colors. Active bottom feeder that eats invertebrates. Grows to 5 inches.

This small sample illustrates the diversity of bottom dwelling fish available. Hundreds of species inhabit the lower levels of the tank in search of food.

Why Are Bottom Dwellers Important?

Bottom dwellers serve several important functions in the aquarium environment:

Best Fish for Cleaning Bottom of Tank Freshwater

As members of the clean-up crew, bottom feeders help consume uneaten foods, debris, residue, and even algae accumulating on surfaces. Their position near the substrate allows them access to bits and pieces that settle and accumulate over time. Many have adaptable mouthparts for vacuuming or grazing these areas.

Species like cory cats, loaches, and plecos make regular passes along the bottom and decorations, clearing away buildup. This helps prevent decaying matter from fouling the water. While no fish “clean” tanks instead of proper maintenance, bottom dwellers help reduce accumulated gunk.

Do Loaches Clean Tanks?

In particular, many aquarists wonder if loaches help clean the tank. The answer is yes—loaches are excellent bottom cleaning fish. Their elongated bodies allow them to slither through tight spaces picking at debris. Those barbels act like little fingers, detecting food sources along the way.

Some loach species like clown and zebra loaches are prized for their waste-eating abilities. That said, no fish should be added solely as a janitor. They need proper nutrition from quality foods too.

Choosing the Right Bottom Dweller

Stocking bottom dwelling fish depends greatly on tank size. Here are some tips:

Best Bottom Feeder Fish for Small Tank

Small tanks under 10 gallons limit options for bottom fish. Pygmy cory cats, dwarf loaches, and small shrimp are best for nano setups. Avoid plecos that grow large.

  • Habrosus Cory – Tiny cory cat, max size 1 inch
  • Pygmy Cory – Minuscule armored catfish with sensitive barbels, max 1 inch
  • Dwarf Chain Loach – Small, peaceful loaches that reach 2 inches
  • Ember Tetra – Mid-level schooling fish but small enough for nano tanks

Bottom Dwelling Fish for 10 Gallon Tank

A 10 gallon tank opens the door for more choices:

  • Kuhli Loach – Basic black kuhlis reach 4-5 inches. Need groups.
  • Otocinclus – Peaceful algae eating catfish. Groups of 6+.
  • Clown Pleco – Small suckermouth catfish, max around 3 inches.
  • Ghost Shrimp – Nearly transparent shrimp help eat debris and algae.

Avoid large plecos and big loach species. Stick with peaceful community fish under 3-4 inches.

Bottom Dwellers Fish Tank Mates

Many bottom dwellers make excellent tank mates for mid to top-level swimming fish. Here are some compatible choices:

  • Tetras: Small schooling fish that occupy the middle to top levels.
  • Rasboras: Active schoolers for the top half of the tank.
  • Danios: Fast moving schooling fish that stay mid to top level.
  • Gouramis: Larger centerpiece fish that only venture to the bottom while grazing.
  • Mollies: Peaceful mid-level livebearers. Avoid fin nippers like tiger barbs.

Avoid housing bottom dwellers with aggressive species prone to attacking fish lower in the tank. Slow moving bottom fish make easy targets for bullies.

Common Bottom Dweller Misconceptions

Numerous myths surround bottom dwelling fish. Let’s clear up some common misconceptions:

Are Betta Fish Bottom Dwellers?

Betta fish often rest on the bottom but are not true bottom dwellers. They have an intricate breathing organ called the labyrinth that allows them to rise to the surface for gulps of air. While bettas may lounge on the bottom, they should not be labeled as bottom fish. A betta wasting too much time on the bottom may indicate poor water quality or health issues.

Hagfish Are Bottom-Dwellers with Poor Eyesight

Though they sound mythical, hagfish are real and demonstrate some unique adaptations to deep sea life. These primitive fish lack true eyes or even a jaw, instead relying on touch via whisker-like barbels. Their whip-like tail allows them to tie knots to scrape food particles from crevices. While fascinating, hagfish are not suited for home aquariums given their strict environmental needs.

Care and Maintenance for Bottom Dwellers

Caring for bottom dwelling fish comes down to a few key considerations:

What is the Best Substrate for Bottom Dwellers?

Substrate choice directly impacts bottom fish. Sharp gravel can damage barbels and undersides. Bare bottom tanks offer no shelter. The best bet is a fine, smooth sand substrate. Soft sands allow fish to sift and search for food without injury. For loaches, provide some rocky caves since they are shy. Simple pool filter sand works well and won’t alter water chemistry.

Beyond substrate, perform regular water changes and tank cleanings. While bottom dwellers eat some waste, they can’t replace basic aquarium maintenance. Use a siphon to remove debris from the substrate during routine water changes. Don’t neglect filter maintenance either.

Freshwater Bottom Feeder Fish Care

For freshwater bottom species, focus on providing a nutritious omnivore diet. Offer a quality flake/pellet along with supplements like:

  • Sinking wafers/pellets to reach the bottom
  • Blanched veggies like zucchini or cucumber
  • Live or frozen foods like brine shrimp, daphnia, or bloodworms

This provides a balanced diet. Overfeeding can foul the water and lead to obesity in fish like plecos. Adjust amounts based on consumption.

Behavioral Observations

Sometimes bottom dwellers exhibit concerning behaviors. Understanding the causes can help aquarists address the issues.

Why Are My Fish Hiding at the Bottom of the Tank?

Fish retreating to the bottom and hiding could stem from multiple problems:

  • Stress: New fish or those added to an established tank may hide until they adjust. Offer plenty of shelters.
  • Aggression: Bullying tankmates stress bottom dwellers. Reduce aggression through proper stocking.
  • Poor Water Quality: Ammonia burns prompt hiding. Perform testing and water changes.
  • Incorrect Parameters: Unsuitable pH, temperature, etc causes hiding. Ensure compatibility.
  • Illness: Sick fish often become lethargic and hide. Look for other symptoms and treat appropriately.
  • Insufficient Food: Hungry bottom dwellers may hide and wait for food to drop. Increase feeding frequency.

Why Is One of My Fish Hiding?

A single fish hiding while others seem fine may indicate bullying. Aggressive tankmates target weak or small fish. Check for signs of physical damage like ripped fins. Remove the bully or break lines of sight with tank decor.

Bottom Dwelling Fish in the Wild

Bottom fish inhabit waterways across the globe, from South America to Africa. Here are some interesting examples:

Bottom Dwelling Fish in North Atlantic

The North Atlantic ocean harbors unique bottom species like Flemish cap cod. These cold water fish sport a barbel on their chin used to detect prey on the seafloor. Their large pectoral fins act like legs, allowing them to perch on the bottom.

Dragonfish also occupy the deep North Atlantic. Ranging from black to brilliant red, they have bioluminescent barbels used to lure prey in the perpetual darkness. Their sharp fangs betray their vicious nature.

Bottom Dwelling Fish with Winglike Fins

Meanwhile, African rift lakes contain extraordinary bottom dwellers like cichlids. Species like the Zebra Obliquidens have elongated, filamentous fins resembling wings. These likely help with stability and maneuverability close to the bottom as they sift through sand and pebbles. Other cichlids like featherfins developed similar adaptations.


Bottom dwelling fish form a fundamental part of freshwater and saltwater setups. While the term implies their vertical positioning, it also hints at their scavenging behaviors. Choosing suitable bottom dwellers, understanding their needs, and clearing up misconceptions equips aquarists to care for them properly. Bottom fish come in endless forms, from catfish to loaches, gobies to blennies. Adding a few helps maintain a cleaner, healthier tank environment.