Hi Mal - Sorry it has been a while since I have been on here...

 

That looks more like viral than bacterial to me (localised, slow growing and the fish act fine) - nothing can be done in general.

 

The sore in front of the eye could be related - (underlying tumour) 

 

It could all be exasperated by stresses due to the territoriality of these fish - either way, it is not that deadly and just increases slowly with age.... but generally not deadly on its own unless a tumour grows int he wrong place.

Hard to tell adequately from the pic - but I note the large eye, fork tail and relatively shorty body structure. Plus the fact that Moore River does regularly join with the sea as it flows out...

I suggest it is at least in the family ARIIDAE
Generally marine origin, but will also head into estuaries- if it was carried south by the Leeuwin Current, it could have entered into the moore river looking for warmer waters...
Strange find indeed....

From what I understand, you top up the tank then add the water conditioner that has been mixed in a bucket... If this is the case, next time, try adding the required amount of water conditioner to the emptied aquarium before topping up with water. Also, if you are using a garden hose to top it up, flush the contents of the hose first before adding water to the tank (plasticisers in the hose can be toxic)
Basically, something toxic is coming through your tap water that is killing off your filter bacteria, causing a spike in ammonia or nitrite.... or so it seems.
So try to change the methods of your water change and see if that improves the situation.

Curious to know how they got up there.... not many people keeping aquarium fish in that neck of the woods.... :|
Either used as bait or someone using them to control mozzies in water holes that overflow during floods.... either way, rare to see green sailfin mollies - most mollies imported and sold for the aquarium trade are coloured.

It is still possible to find G. munda in some random pockets in areas that gambusia have not reached... yet...

That will boost the pH - so still use with caution....

Personally, I'd use a minimum amount and increase the dose rate each 2nd day for the same batch of peroxide until you get the results you are after. (Heavy aeration will also help reduce the oxygen levels if too high).


The general dose rate for 50% peroxide is 3ml of solution per 100Litres of aquarium.

Peroxide loses its %'age over time - so start with the initial dose and increase it by a small margin every few days until you notice a suitable result... then continue with that dose rate until the bottle is empty..... start from the original dose rate with a new bottle.