# Hatchet Fish and high flow



## alanchown (27 Jan 2020)

I have a 200l with an FX4, so flow and surface movement is high. 
Has anyone experience of Hatchet fish in high flow. I suspect it's a no no.

Alan


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## Zeus. (27 Jan 2020)

Yes I have hatchet fish and high flow 500l FX6 and maxspect gyre XF330 X2 and they cope fine. The high flow isn't 24/7 as the gyres run on schedule. When flow is high for short periods during day they just find spot in tank with low flow. Otherwise their near the surface. If flow was high 24/7 well that's another story OFC


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## alanchown (27 Jan 2020)

It would be 24/7. Not much I can do about that. In a smaller tank opportunity to get out of flow at the surface is limited. My Tetras have no issue.


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## Siege (27 Jan 2020)

@Geoffrey Rea will be able to add.


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## mort (28 Jan 2020)

They like cover and especially floating plants, so I'd judge the suitability on whether you can support floating plants with the flow or whether it's to strong and they are pushed under the water. If the floaters are fine then the fish should be as well because they can handle currents in nature.
You can also use taller plants or hardscape to deflect some of the flow and create sheltered areas. Are you using a spray bar or smaller outlet?


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## Geoffrey Rea (28 Jan 2020)

alanchown said:


> Has anyone experience of Hatchet fish in high flow. I suspect it's a no no.



Yes. If you’re attempting to make them comfortable you can create a dead spot in surface flow. If it’s a spray bar you’re using blank off a couple of the holes with electrical tape. Hatchets are God’s in drag efficiency, they don’t need much of a dip in current to be comfortable.

If it’s lily pipes and it’s two sets, have them diametrically opposed. If it’s one lily pipe, put a power head/eheim skimmer/small pump at the opposite corner. Creates calm mid tank at surface level.

This all is based on presuming a lot about your setup but principles still apply.

Watched hatches sit in the full blast of a 3000 lph pump for the hell of it. Barely flicking a fin to maintain position, quite remarkable little creatures. But some respite from high flow is a good goal for the setup if you want them happy.



mort said:


> You can also use taller plants or hardscape to deflect some of the flow and create sheltered areas.



@mort ’s suggestion is excellent. Any plants growing out the of water also provide shade from your lighting, fish don’t have eye lids and surface dwellers get the brunt of it. Also good rolling dry food down leaves (swords) as they seem to get a buzz from being fed in a more natural way.


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## alanchown (28 Jan 2020)

I have a standard FX4 outflow- but I do have Vallis and Rotala and pogestomon erectus hat grows to the top. Usually have a small clump of hornwort floating as well. I need to think about it.


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## Geoffrey Rea (28 Jan 2020)

If I remember correctly the FX4 comes with two adjustable jets that attach to the end of the rib hosing...?

If the goal was reducing the impact of flow without reducing turnover then replacing the standard fitting with a 90 degree pvc pipe of the right diameter would achieve this:






Wide bore allows high return rate in a non concentrated manner.


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## dw1305 (28 Jan 2020)

Hi all, 





Geoffrey Rea said:


> Watched hatches sit in the full blast of a 3000 lph pump for the hell of it. Barely flicking a fin to maintain position, quite remarkable little creatures.


I kept Marbled Hatchets for a while, and they always used to <"sit in the flow from the spray bar">.

They are <"very entertaining to watch">. 

cheers Darrel


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## Geoffrey Rea (28 Jan 2020)

dw1305 said:


> I kept Marbled Hatchets for a while, and they always used to <"sit in the flow from the spray bar">.



Makes sense... let the food come to you 

Oxygen rich water too.


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## alanchown (28 Jan 2020)

Tempted to give it a go. My Vallis is now more than reaching the surface which will break the flow. I have Rotala in front of the outlets which must disperse flow.


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