Pack size
300 g
Cost per litre treated
3.5c
Water type
Brackish + Freshwater
Bottle treats
600 L
Dose rate
20 g per 40 L
Shrimp and invert safe
Caution, per Seachem
Plant safe
As directed, per Seachem
Pack size
600 g
Cost per litre treated
3.4c
Water type
Brackish + Freshwater
Bottle treats
1200 L
Dose rate
20 g per 40 L
Shrimp and invert safe
Caution, per Seachem
Plant safe
As directed, per Seachem
Pack size
4 kg
Cost per litre treated
1.8c
Water type
Brackish + Freshwater
Bottle treats
8000 L
Dose rate
20 g per 40 L
Shrimp and invert safe
Caution, per Seachem
Plant safe
As directed, per Seachem
Seachem Brackish Salt
Brackish water done by the gram, not by guesswork. Seachem Brackish Salt is a mineral blend for estuary fish – livebearers, archers, chromides, monos, scats and Datnioides. It contains minimal sodium chloride, so it is not the same thing as tonic salt or marine salt mix, and at the published livebearer rate it does not harm aquarium plants. Sold in 300 g, 600 g and 4 kg.
Key features
- Dosed by species, not by specific gravity – Seachem publishes a gram-per-litre rate for each group of estuary fish, so you weigh rather than float a hydrometer
- Minimal sodium chloride – it supplies the broader mineral profile of an estuary rather than just salting the water
- Plant-safe at directed rates – the livebearer and general rates will not damage aquatic plants, which is unusual for a brackish product
- No effect on pH or KH – it does not buffer, so it will not fight a pH regime you have already set
- Three sizes – 300 g for a single livebearer tank up to 4 kg for a stocked brackish system
- Under 2c per litre at 4 kg – at the general/livebearer rate the 4 kg pack works out to about 1.7c per litre of brackish water, against 3.4c per litre from the 300 g starter size
Specifications
| Product type | Brackish mineral salt blend |
|---|---|
| Sizes | 300 g, 600 g, 4 kg |
| Sodium chloride content | Minimal |
| Effect on pH | None – does not buffer |
| Effect on carbonate hardness | None |
| Plant safety | Safe at directed rates, except the scat dose |
| General aquarium rate | 20 g per 40 L |
| Water type | Brackish and freshwater |
Dosage and directions
Dissolve the salt in fresh water before it goes into the tank. On an established aquarium, bring the level up gradually over several water changes rather than in one hit. Do not add salt when you are only topping up evaporation – the salt does not evaporate, so topping up with more salt raises the concentration each time.
| Fish group | Dose | Household measure |
|---|---|---|
| Livebearers – guppies, swordtails, platies, some mollies | 20 g per 40 L | About 1 tablespoon |
| Yucatan and Sri Lankan estuary fish – archers, chromides, some mollies | 15 g per 12 L | About 2 teaspoons |
| Thai, Cambodian, Bornean and Sumatran fish – Datnioides | 40 g per 12 L | About 2 tablespoons |
| Scats | Up to 80 g per 12 L | About 4 tablespoons |
| General aquarium use | 20 g per 40 L | About 1 tablespoon |
The scat dose is not for planted aquariums. For a mixed brackish community, use an average dose representative of the species present rather than the highest one.
Which size do I need?
How far a pack goes depends entirely on which rate you are dosing at. Figures are rounded down.
| Pack | Livebearers, 20 g/40 L | Archers and chromides, 15 g/12 L | Datnioides, 40 g/12 L | Scats, 80 g/12 L | Cost per litre, general rate |
|---|---|---|---|---|---|
| 300 g | 600 L | 240 L | 90 L | 45 L | 3.4c per litre |
| 600 g | 1,200 L | 480 L | 180 L | 90 L | 3.4c per litre |
| 4 kg | 8,000 L | 3,200 L | 1,200 L | 600 L | 1.7c per litre |
A 200 L scat tank takes roughly 1.3 kg to set up at the full scat rate, which puts most scat keepers straight onto the 4 kg pack.
Suitable for, and not suitable for
Suitable for: brackish community tanks · livebearer tanks where a light mineral load is wanted · archers, chromides, monos, scats and Datnioides · planted brackish setups, at the livebearer and general rates.
Not suitable for: marine aquariums, where a full synthetic sea salt is required · planted tanks at the scat dose · use as a freshwater tonic salt, which is a different product at a different rate · topping up evaporation.
What we could not verify
Seachem does not publish an elemental analysis for Brackish Salt, so this page states the dose rates and the composition claims the manufacturer makes, and no figures beyond them. If you need a target specific gravity for a species, dose by weight from the table above and measure the result in your own tank.
Care and storage
- Keep the container sealed – the blend takes up moisture and will cake if left open
- Weigh rather than scoop where you can; the tablespoon equivalents are approximate
- Dissolve fully before adding, so undissolved grains do not settle on plants or substrate
Goes well with
- Seachem Prime – conditions the fresh water you dissolve the salt into
- Seachem Stability – salinity changes knock a biofilter about, so support it while you raise the level
- Seachem Cichlid Lake Salt – the Rift Lake equivalent, for African cichlids rather than estuary fish
- Seachem American Cichlid Salt – for soft-water Central and South American cichlids
- Seachem MultiTest: Ammonia – worth watching while the biofilter adjusts to a new salinity
Warranty and delivery
This product carries the consumer guarantees under the Australian Consumer Law, which cannot be excluded. Contact us if a pack arrives damaged or has hardened in transit.
The 300 g and 600 g ship as standard parcels. The 4 kg is a heavier parcel and is charged accordingly. No dangerous goods restrictions apply.
Common questions
How much Brackish Salt do I use per litre?
It depends on the fish. Livebearers and general use call for 20 g per 40 L, which is 0.5 g per litre. Archers and chromides take 15 g per 12 L, and scats can go up to 80 g per 12 L.
Will it harm my aquarium plants?
Not at the livebearer or general rates, which Seachem states are safe for aquatic plants. The scat dose is the exception and is not for planted tanks.
Is this the same as aquarium tonic salt?
No. Tonic salt is essentially sodium chloride. Brackish Salt contains minimal sodium chloride and supplies a broader mineral profile, so the two are not interchangeable at the same dose.
Does it change pH?
No. It does not buffer and does not raise carbonate hardness, so your existing pH regime stays as it is.
Can I add it straight to the tank?
Dissolve it in fresh water first. On an established tank, raise the level gradually across several water changes rather than in one dose.
Do I add more when the water evaporates?
No. Salt does not evaporate, so top up with fresh water only. Adding salt to replace evaporation raises the concentration a little more each time.




