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Best Hard Water Aquarium Fish

Edited by Ivan F.

If your tap water is hard, choosing fish that are happy in it is much easier than trying to soften it.

How we pick: Species whose sourced hardness range reaches at least 15 dGH.

Fitting the same tank size does not mean these species can live together. Check each species' tank mates before you buy.

Pea Puffer
Carinotetraodon travancoricus
Min tank
3.3 US gal
Group
Single fish
pH
6.8–8
Swim zone
Mid-Water
IntermediateTerritorial/Aggressive
African Dwarf Frog
Hymenochirus boettgeri
Min tank
10 US gal
Group
3+ fish
pH
6.5–7.8
Swim zone
Bottom
EasyPeaceful
Apistogramma Borellii
Apistogramma borellii
Min tank
11 US gal
Group
2+ fish
pH
5–8
Swim zone
Bottom
IntermediateSemi-Aggressive
Betta
Betta splendens
Min tank
11 US gal
Group
Single fish
pH
6–8
Swim zone
Top
EasyTerritorial/Aggressive
Celestial Pearl Danio
Danio margaritatus
Min tank
11 US gal
Group
6+ fish
pH
6.5–7.5
Swim zone
Mid-Water
EasyPeaceful
Endler's Livebearer
Poecilia wingei
Min tank
11 US gal
Group
3+ fish
pH
7–8.5
Swim zone
Top
EasyPeaceful
Fancy Guppy
Poecilia reticulata
Min tank
11 US gal
Group
3+ fish
pH
7–8.5
Swim zone
Top
EasyPeaceful
Cherry Barb
Puntius titteya
Min tank
14 US gal
Group
6+ fish
pH
6–8
Swim zone
Mid-Water
EasyPeaceful
Dwarf Neon Rainbowfish
Melanotaenia praecox
Min tank
14 US gal
Group
6+ fish
pH
6.8–7.5
Swim zone
Mid-Water
EasyPeaceful
Forktail Blue-Eye Rainbowfish
Pseudomugil furcatus
Min tank
14 US gal
Group
8+ fish
pH
7–8
Swim zone
Top
IntermediatePeaceful
Honey Gourami
Trichogaster chuna
Min tank
14 US gal
Group
2+ fish
pH
6–7.5
Swim zone
Top
Absolute BeginnerPeaceful
Platy
Xiphophorus maculatus
Min tank
14 US gal
Group
3+ fish
pH
7–8.2
Swim zone
Top
Absolute BeginnerPeaceful
Pristella Tetra
Pristella maxillaris
Min tank
14 US gal
Group
6+ fish
pH
6–7.5
Swim zone
Mid-Water
EasyPeaceful
White Cloud Mountain Minnow
Tanichthys albonubes
Min tank
14 US gal
Group
10+ fish
pH
6–8.5
Swim zone
Mid-Water
EasyPeaceful
Dwarf Gourami
Trichogaster lalius
Min tank
15 US gal
Group
Single fish
pH
6–7.5
Swim zone
Top
IntermediateSemi-Aggressive
Glowlight Tetra
Hemigrammus erythrozonus
Min tank
18 US gal
Group
6+ fish
pH
5.5–7.5
Swim zone
Mid-Water
EasyPeaceful
Albino Corydoras
Corydoras aeneus (albino)
Min tank
19 US gal
Group
6+ fish
pH
6–8
Swim zone
Bottom
Absolute BeginnerPeaceful
Bronze Corydoras
Corydoras aeneus
Min tank
19 US gal
Group
6+ fish
pH
6–8
Swim zone
Bottom
Absolute BeginnerPeaceful
Serpae Tetra
Hyphessobrycon eques
Min tank
19 US gal
Group
12+ fish
pH
5–7.5
Swim zone
Mid-Water
EasySemi-Aggressive
Tiger Barb
Puntigrus tetrazona
Min tank
19 US gal
Group
8+ fish
pH
5–8
Swim zone
Mid-Water
EasySemi-Aggressive
Goldfish
Carassius auratus
Min tank
20 US gal
Group
Single fish
pH
6.5–7.5
Swim zone
All Levels
EasyPeaceful
Blue Gourami
Trichopodus trichopterus
Min tank
21 US gal
Group
Single fish
pH
5.5–8.5
Swim zone
Top
EasySemi-Aggressive
Gold Barb
Barbodes semifasciolatus
Min tank
21 US gal
Group
8+ fish
pH
6–8
Swim zone
Mid-Water
EasyPeaceful
Molly
Poecilia sphenops
Min tank
21 US gal
Group
3+ fish
pH
7–8.5
Swim zone
Top
EasyPeaceful
Pearl Gourami
Trichopodus leerii
Min tank
21 US gal
Group
2+ fish
pH
5.5–8
Swim zone
Top
EasyPeaceful
Rummy Nose Tetra
Hemigrammus rhodostomus
Min tank
21 US gal
Group
10+ fish
pH
5.5–7
Swim zone
Mid-Water
EasyPeaceful
Zebra Danio
Danio rerio
Min tank
21 US gal
Group
8+ fish
pH
6–8
Swim zone
Mid-Water
EasyPeaceful
Boesemani Rainbowfish
Melanotaenia boesemani
Min tank
29 US gal
Group
6+ fish
pH
7–8
Swim zone
Mid-Water
IntermediatePeaceful
Congo Tetra
Phenacogrammus interruptus
Min tank
29 US gal
Group
6+ fish
pH
6–7.5
Swim zone
Mid-Water
EasyPeaceful
Swordtail
Xiphophorus hellerii
Min tank
29 US gal
Group
3+ fish
pH
7–8
Swim zone
Top
IntermediateSemi-Aggressive
Angelfish
Pterophyllum scalare
Min tank
53 US gal
Group
6+ fish
pH
6–7.4
Swim zone
Mid-Water
EasyPeaceful
Siamese Algae Eater
Crossocheilus oblongus
Min tank
80 US gal
Group
6+ fish
pH
6–7.5
Swim zone
Bottom
IntermediatePeaceful