Aquariums can house a surprising variety of life and materials beyond fish. Freshwater shrimp, snails, frogs, live plants, driftwood, and carefully chosen rocks all create a more dynamic, natural-looking tank while serving practical roles like algae control and water quality management. Here’s a breakdown of the best options and what each one actually does for your setup.
Freshwater Shrimp
Shrimp are one of the most popular non-fish additions to a freshwater tank. The two species you’ll encounter most often are Amano shrimp and cherry shrimp (a color variant of Caridina cantonensis). Amano shrimp grow to about 5 cm and are tireless algae eaters, though they’re not especially colorful. Cherry shrimp stay smaller at around 3 cm but come in vivid reds, oranges, and yellows that stand out against a planted background.
Both species thrive in temperatures between 17 and 27°C (roughly 63 to 81°F) and tolerate a wide range of water hardness. Cherry shrimp will breed readily in your tank as long as there’s enough cover and food for the young. Amano shrimp are unlikely to reproduce at home because their larvae need brackish water to survive.
One critical safety note: shrimp are extremely sensitive to copper. Acute lethal concentrations for crustaceans can be as low as 0.1 mg per liter. That means tap water treated with copper pipes, certain fish medications containing copper, and fertilizers with trace copper can all be dangerous. If you keep shrimp, check any product label for copper before adding it to the tank.
Snails for Algae Control
Snails pull double duty as both interesting tank inhabitants and a living cleaning crew. Nerite snails are the most commonly recommended option. They’re aggressive algae grazers that will work over glass, rocks, and decorations. They also can’t reproduce in freshwater, so you won’t end up with hundreds of them overtaking your tank.
Mystery snails are another solid choice, particularly for dealing with diatom and string algae. They’re larger, more visible, and come in gold, ivory, blue, and purple varieties. Unlike nerites, mystery snails can lay eggs above the waterline, so check your tank lid regularly if you don’t want surprise clutches. Ramshorn snails are a smaller, low-maintenance option, though they reproduce quickly and can become a nuisance in some setups.
All snails need calcium to maintain their shells. For a tank with mystery snails, plan on offering a calcium supplement tablet for roughly every five snails, two to three times per week. Ramshorn snails need less, about one tablet per fifteen snails at the same frequency. If you notice thin, pitted, or eroding shells, your water likely lacks enough calcium and you should increase supplementation or add a mineral source like cuttlebone.
African Dwarf Frogs
If you want something with a bit more personality, African dwarf frogs are fully aquatic amphibians that do well in community tanks with peaceful fish. They stay small and spend most of their time near the bottom, occasionally darting to the surface for air.
A single frog needs at least 2.5 gallons, and a pair should have 5 gallons. One important detail: avoid tanks deeper than 12 inches. These frogs are not strong swimmers and need easy access to the surface to breathe. Water temperature should stay between 72 and 78°F with a pH of 6.5 to 7.8.
Their diet is high-protein: sinking frog pellets (look for 40 to 50 percent protein content), freeze-dried bloodworms, frozen brine shrimp, and live blackworms. Feed once a day or every other day. Their stomachs are tiny, so overfeeding leads to water quality problems fast. If you don’t use a filter, plan on weekly water changes. With a filter, changing 10 to 25 percent of the water every two to four weeks is sufficient.
Live Plants
Live plants transform both the look and the chemistry of your aquarium. They absorb nitrates produced by fish waste, oxygenate the water during daylight hours, and give shrimp and fry places to hide. For beginners, low-light species like Java fern, Anubias, and Java moss are nearly indestructible and don’t require specialized equipment.
Your substrate choice matters if you plan to grow rooted plants. Active substrates (aqua soils) contain nutrients that plant roots can absorb directly, but they leach ammonia during the first few weeks, which means you need to cycle the tank before adding any animals. They also deplete over time and eventually need replacing or supplementing with fertilizer. Inert substrates like sand, gravel, or crushed lava rock last indefinitely but don’t supply nutrients on their own. You’ll need root tabs or liquid fertilizers to feed your plants. Crushed lava rock and fired clay are particularly good inert options because their porous surface promotes healthy root growth.
If you’re setting up your first planted tank, inert substrate with root tabs is the simpler path. Active soils give faster, lusher growth but require more understanding of how they affect pH and ammonia levels.
Driftwood
Driftwood adds a natural, aged look to any aquarium and provides surfaces for beneficial bacteria, mosses, and algae that shrimp love to graze on. The type you choose affects your water chemistry, though, so it’s worth knowing the differences.
Mopani wood and standard bogwood both release tannins, organic compounds that tint the water a tea-like amber color and gradually lower pH. Some fishkeepers love this “blackwater” effect because it mimics the natural habitat of species like bettas, tetras, and discus. If you’d rather avoid the color shift, soak the wood in a bucket for several days to a few weeks before adding it, changing the water periodically until it runs mostly clear.
Spider wood (also sold as azalea root) is a popular alternative because it doesn’t release tannins or change pH. It does float when first submerged, so you’ll need to soak it or weigh it down until it becomes waterlogged. Its branching, tree-like shape makes it especially popular in aquascaping.
Rocks and Stone
Nearly all natural rocks are aquarium-safe without any special treatment. Granite, slate, quartz, river stone, lava rock, and petrified wood can all go straight into the tank. The only stones to genuinely avoid are malachite and azurite, which can leach copper (a serious concern if you keep invertebrates).
Rocks that contain calcium carbonate will slowly raise your water’s pH and hardness. You can test for this by dropping vinegar on the rock: if it fizzes, it contains calcium carbonate. Common examples include limestone, Seiryu stone, coral rock, marble, and travertine. These stones will typically push pH up to around 7.6 to 7.9, which is perfectly fine for most community fish and actually beneficial for African cichlids and livebearers that prefer harder water. If you keep soft-water species or shrimp that need a lower pH, stick with inert stones like granite or lava rock that won’t alter your water chemistry.
What to Avoid Putting in Your Tank
Not everything that looks decorative is safe underwater. The biggest risks come from materials that slowly leach chemicals into the water column:
- Painted items not made for aquariums. Paint can flake off over time and release heavy metals or solvents. If a decoration wasn’t specifically manufactured for aquarium use, the coating is suspect.
- Plastic toys and figurines. Standard plastics can release plasticizers when submerged for long periods. That action figure or building block might look fun, but it’s not formulated to sit in warm water for months.
- Lead-glazed ceramics. Some pottery glazes contain lead that leaches into water. Unless a ceramic piece is certified food-safe or explicitly labeled for aquarium use, skip it.
- Malachite and azurite stones. Both are copper-based minerals. Even small amounts of dissolved copper are lethal to shrimp and snails.
When in doubt, the simplest rule is to use materials marketed for aquariums or materials that are chemically inert, like natural stone, untreated wood, and food-grade stainless steel. If something has a coating, dye, or glaze you can’t verify, it’s not worth the risk to your tank’s inhabitants.