Can Australian Smelt and Knight Goby Live Together?

Possible with Caution

Keeping Australian Smelt and Knight Goby together is possible but requires caution due to differing aggression levels. Provide a spacious tank of at least 75 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

Australian Smelt

Retropinna semoni

Knight Goby

Stigmatogobius sadanundio

🐠Family Group
Australian Smelt
Other
Knight Goby
Gobies & Gudgeons
Temperament
Australian Smelt
Peaceful (1/10)
Knight Goby
Semi-Aggressive (6/10)
Temperature
βœ“ Compatible
Australian Smelt
15–24Β°C
Knight Goby
20–28Β°C
pH Range
βœ“ Compatible
Australian Smelt
6.5–8
Knight Goby
7–8.5
Hardness (dGH)
βœ“ Compatible
Australian Smelt
5–20
Knight Goby
10–30
Water Type
βœ“ Compatible
Australian Smelt
Brackish Tolerant
Knight Goby
Brackish Tolerant
Flow Preference
βœ“ Compatible
Australian Smelt
Moderate
Knight Goby
Moderate
Min Tank Volume
Combined: 75 L
Australian Smelt
75 L
Knight Goby
75 L
Swimming Level
Shared: 1 zone
Australian Smelt
TopMiddle
Knight Goby
MiddleBottom
🏷️Behavior Tags
Australian Smelt
Hyperactive / Fast SwimmerShy / Slow Moving (Easily Stressed)Fry PredatorJumper (Lid Required)
Knight Goby
Fin NipperShrimp EaterFry PredatorTerritorial (Defends specific area)Digger (Disturbs Substrate)Aggressive to same species/look-alikes
Stocking calculator

Can your tank handle Australian Smelt and Knight Goby?

Compatibility is only part of the answer. Test both fish with your real tank size, current stock, and maintenance needs to see if you have enough space and a safe stocking level before you add them.

Australian Smelt
Knight Goby
Test both in my tank

Behaviour & Temperament

Australian Smelt is a peaceful species (1/10), while Knight Goby is moderately assertive (6/10). This notable difference means Knight Goby may occasionally assert dominance over Australian Smelt.

Australian Smelt and Knight Goby both frequent the Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Worth noting: Australian Smelt is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Australian Smelt and Knight Goby to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations. A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat. Keep fin nippers in larger groups to distribute nipping behaviour among conspecifics rather than tank mates.

Water Parameters

The safe temperature window for both species falls between 20Β°C and 24Β°C. Aim for the midpoint of this range (around 22.0Β°C) for optimal comfort.

Both fish can tolerate a pH between 7 and 8. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 10–20 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Australian Smelt and Knight Goby together, plan for an aquarium of at least 75 litres with a minimum length of 60 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots β€” caves, driftwood, and dense plant clusters β€” so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Plants - lighly covered, Smooth Gravel (Sensitive Barbels), Sand (Sifters), Shells (Breeding/Hiding), Driftwood (Digestion/Hiding). Meeting these requirements will help both species thrive.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Suitable Tank Sizes

Standard aquarium sizes large enough for both Australian Smelt and Knight Goby.

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Frequently Asked Questions

Can Australian Smelt and Knight Goby live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 75 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do Australian Smelt and Knight Goby need?

A minimum of 75 litres (tank length at least 60 cm) is recommended. This provides enough space for both species to establish their own areas and reduces the likelihood of territorial disputes.

What water temperature is best for Australian Smelt and Knight Goby together?

Keep the aquarium between 20Β°C and 24Β°C. A target of around 22.0Β°C sits comfortably within both species' preferred ranges.

Are Australian Smelt or Knight Goby aggressive?

Australian Smelt is peaceful (1/10) and Knight Goby is moderately assertive (6/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Australian Smelt and Knight Goby need?

Both species overlap in the 7–8 pH range. Consistency is key β€” avoid sudden swings, and test regularly to stay within this window.

Will Knight Goby nip Australian Smelt's fins?

Knight Goby is a known fin nipper. If Australian Smelt has long or flowing fins, there is a real risk of fin damage. Keeping Knight Goby in a larger group can help redirect nipping behaviour toward conspecifics.

How do I manage Knight Goby's territorial behaviour?

Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Knight Goby space to claim a territory without encroaching on the other fish's area. Adding dΓ©cor that divides the tank into distinct zones works especially well.


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