Rainbow Trout at Cotter River, ACT
Identification history
| Oncorhynchus mykiss | 17 Oct 2023 | MattBeitzel | ||
| Galaxias sp. (genus) | 17 Oct 2023 | Ct1000 |
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User's notes
Probably a stretch to get a specific species especially with a phone photo. Tail had a golden /red colour. Black stripes or barring down the sides.
8 comments
MattBeitzel
wrote:
17 Oct 2023
Its a juvenile Rainbow trout by the par markings and the fin alignment. Lack of a red tinge to the adipose fin indicates its not a brown trout.
MattBeitzel
wrote:
17 Oct 2023
Yes it would have hatched at the end of august. There are galaxias in that catchment but not usually where the trout are. There are native fish at that location if your quiet and careful.
Ct1000
wrote:
18 Oct 2023
Yeah I believe I saw a two-spined black fish there last year sometime but didn't get a photo. But definitely in that location both trout species seem to be the dominant species. Do you know anything about shrimp? That night on the weekend was the first time I didn't manage to see any shrimp (the glass shrimp species paratya) at that location on a night visit and I was wondering if I just didn't see them or the deeper water, seasonal change or some other factor might be effecting their numbers there.
Ct1000
wrote:
18 Oct 2023
Also what kind of fin arrangement helps differentiate between galaxias and trout at that size?
MattBeitzel
wrote:
18 Oct 2023
Galaxias only have one fin on their back and its situated well to the rear, overlapping the anal fin. This has a dorsal fin more to the mid section of the body and there is an adipose fin (a small thumb shaped fin) on the caudal peduncle (fleshy bit in front of the tail) on a fish this size the adipose its pretty small but you can see it in the photo. The fin on the underside under the dorsal isnt the anal fin its the pelvic fin and it should be paired but that cant be seen in the photo. For a phone photo in the water its pretty good for such a small fish. If it were a galaxias the only back fin would start about where the dorsal on this fish ends. As far as we know from genetic analysis all ACT galaxias are G. olidus. and we have a pretty broad sample across the ACT.
MattBeitzel
wrote:
18 Oct 2023
Blackfish and Macquarie perch are pretty common at that location. Shrimp are difficult to work out what causes peaks in populations as some years there are tonnes of them but I wouldn't expect them to be particularly common coming out of winter.
Location information
- Coordinates 148.889832-35.346306
- Altitude 587.4m
- Maps Lower Cotter Catchment
- Places Cotter River, ACT
Sighting information
- 4 - 15 Abundance
- 14 Oct 2023 08:21 PM Recorded on
- Ct1000 Recorded by
-
Collections
Fish Trout and Salmon Exotic Fish Ct1000 Canberra & Southern Tablelands NatureMapr Oncorhynchus mykiss
Additional information
- Less than 1m Depth of sighting
Species information
- Oncorhynchus mykiss Scientific name
- Rainbow Trout Common name
- Not Sensitive
- Exotic
- Non-invasive or negligible
- Up to 1220.9m Recorded at altitude
Record quality
- Images or audio
- More than one media file
- Verified by an expert moderator
- Nearby sighting(s) of same species
- GPS evidence of location
- Description
- Additional attributes