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Flounder, Platicthys flesus

Irish Record Fish: We have withdrawn the details on the Irish record and specimen weights as the current IFSC rules require anglers kill all such fish, hardly sporting or conservation minded, is it?  Alternatives exist.
Boat Specimen:
Shore Specimen:
Photo Credit:

Kieran Hanrahan, Ferry Point, Youghal, March 2004

Introduction: The Flounder is well known for its preference for brackish estuarine waters and it can often be found well up tidal rivers, even in some seaside lakes... it is also one of the earliest appearing species and can be caught all year round and in daylight.  Sandy river estuaries will harbour 'flukes', but we have also caught them on incoming tides in small harbours on the west coast, often in remarkable numbers!  They are not fastidious eaters and will tackle just about anything edible and they are not put off by big hooks and big baits either - you would be amazed what the can cram into their gapes.  Often you get rattling good bites but flatfish, and flukes in particular are known to cosy up and quietly engulf a bait, not even moving when hooked, intent on wolfing it down!  This often leads to deeply hooked fish, which is why many anglers are now using small circle hooks in an attempt to maximise lip hooking and simplify catch and release. With circle hooks, which are self hooking and ideally used for predators that really attack a bait, often the flounder has gagged on the bait and is not hooked at all, however if you do encounter a flounder that is deeply hooked, try going in through the gill cover with a forceps.  They are remarkably tough fish.

How do you tell them apart?  Flounder are easily identified in that they have no spots and grow to a reasonable size.  They can on occassion be double sided, i.e. have no white colour underneath. In some locations, it has been estimated that up to 5% of the fish display this curious genetic anomaly, indeed once in a busy fishing lifetime you even come across the odd "albino" which is totally white. These are very rare since their colouration fails to camoflague them properly from standard predators like Tope and Seals. Very occassionally you come across flounders that have the odd spot, akin to plaice.  It has been suggested that some flatfish interbreed causing this curiousity or that it is a genetic throwback.  Certainly identification can be tricky so we are indebted to shockleader50  for the following excellent method for clearly establishing the species you have caught: -

"Easiest way to tell is by touch.
Start at the tail and rub your finger right up the back bone.
A Flounder has small lumpy nodules the whole way up this line and is smooth on each side of the line.
A Plaice is totally smooth the whole way to the head ,where there are some of these lumpy nodules.
A Dab is rough all over, the whole way up.
Even if fishing in the dark this can make identification quite easy."

Boat tactics: A decent Flounder is the match for any Plaice and far surpasses the Dab - it will tackle any bait with plain ragworm offering you the best bet over rougher ground and lugworm a decent backup over sand - you have to keep the hook size down to perhaps a set of 1/0 or 2/0 in a pennel rig for Flounder, smaller in competition or  if you suspect the presence of Sole.  They do not grow to the same size as Plaice, with anothing over 1 kilo an excellent fish, and tend to be caught inshore rather than on mussel beds. Flounder are inquisitive fish and addition of coloured beads, sequins and flasher spoons to the rigs, typically on the final snood just above the lead, will assist in attracting fish.  Some people even use rattles attached above the bait to generate a distubnance in the water.  A watch lead stirring up the mud attracts fish too. Off a boat at anchor a plain lead would allow the baits to move around, whereas on a slow drift over clean ground the watch lead does the trick. Standard flatfish rigs, two up one down for example, will hook Flounders.  Crab works wonders inshore and if often the only bait that will work.

Shore tactics: An estuary rather than a beach is ideal and a decent beachcaster and reel, loaded with worm baits on 1/0 or 2/0 hooks, with a watch lead and flasher spoon is how to find Flounder.  You can move down to a spinning rod and lighter tackle or a bass rod if you prefer so long as there is not too much weed or snags.  Flounder are not as common on the western storm beaches, albeit a small stream or river adds to a mark's potential for Flounder, and always try botttom fishing any sandy harbours on an incoming tide.  Flounder react to disturbances in the sand or mud, and it is worthwhile on snag free marks to bring your baits back in a stepped retrieve, pausing every few turns for 30 seconds to allow the flounder find the bait.  In estuaries half a peeler crab whipped on with shirring elastic is an excellent bait.  If you have fresh peelers as opposed to the tin foil wrapped variety, the legs and claws are a superb flounder bait.  The only time when Flounder get tricky is around the end of autumn, when they will get more choosy about their diet. By March, after spawing, they will tackle anything!  Unlike the Plaice which shows a definite preference for clear water, Flounder will often be taken in heavily coloured water, which is not to say that a clamer day will produce better fish, because invariably it will, the same for all of our flatfish.  Calm weather means flatfish.

More recently there has been several discussions on whether air pressure affects fishing.  Certainly the concensus appears to be that high pressure has the effect of sending fish lower in the water column or out into deeper water.  I do not think that this applies to Flounder, since they often follow the exact same route through a channel each and every day on every tide.  It is quite easy to catch the same fish several days in a row on some of the smaller marks.  On mudflats after neap tide you will often find the frilly marks left by a flatfish that has moved quickly over the seabed, a handy indicator as to its size and patrol patterns.  Once thing that does affect the fishing is an excess of fresh water and particularly heavily coloured or bog water entering an estuary.  At best you should fish around it, on the margin and certainly not into it.  If the spate is particularly strong, you should pack and try another mark as very high volumes of fresh water either drive the fish away or put them off feeding.