Platy fish laying on the bottom of tank

[Ignia]

Hi, I'm new here and I have a question about my platy fish. I have my platy fish for one year and 2 months. He has my first fish and has survived when others died so he is a fighter.
For a month that he (is a male) is laying at the bottom of the tank. He got thinner on the part of the body close to tail and very bumpy its like its dented.. . He still hungry and eats well. He only swims to look for food and the rest of the time he is laying on the bottom.
I test the water regularly and it's all fine. Even ammonia it's fine.
Change 10% of water every week.
It's just one fish and 2 amano shrimps.
My tank is 30L.
I started using RO water 4 months ago due to my tap water being high in nitrates.
3 months ago I started having brown algae and had to turn lights off and took out floating plant so the growth of algae could stop. I keep the lights off too. But there's plenty of light during all day.
I had to take out the lava rock because he was hidding under it and started scratching.... He likes to be with the head under the water stone but with vibration he got a little bump in his head...
He answers to me, when he sees me he search for food and swim but gets tired easily and then goes down again.
I went to some fish shops but no one can help. One told me he must be getting old???
Oh, I'm adding some vitamins too. I added salt 2 weeks ago but only half dose due to my shrimps, one of them is pregnant.
I will send video and pictures.
I care so much for this little one, I would appreciate so much if I could get help.
Thank you.
Oops the videos are too big...

 

[NannaLou]

I think platies prefer harder water and the change to the RO water is probably causing him some stress. Are you re-mineralising the RO water? If not I think that might effect the shells on the shrimp too.

Someone with more concrete knowledge will give mores details.

 

[otterblue]

This may not be the reason but he might be missing the cover he previously had. Since the lava rock and plant are gone he may be stressed. Perhaps you can put in more plants and wood/rock for him to hide behind. That way he'll feel more secure.

 

[Ignia]

I think platies prefer harder water and the change to the RO water is probably causing him some stress. Are you re-mineralising the RO water? If not I think that might effect the shells on the shrimp too.

Someone with more concrete knowledge will give mores details.

Thank you for your answer. I think it's always added minerals but will check. Thank you.

 

[Ignia]

This may not be the reason but he might be missing the cover he previously had. Since the lava rock and plant are gone he may be stressed. Perhaps you can put in more plants and wood/rock for him to hide behind. That way he'll feel more secure.

Thank you for your answer. Unfortunately I can't have the plants because if I put the lights on the brown algae will spread all over the aquarium.In just 5 hours the water gets all brownish. I thought my platy could feel lonely but I'm afraid if I get another fish now, he will attack because my platy is weak.
The lava rock was small and it was just because of bacteria he never got close to it or hide under... Only started when his behaviour changed. He has the coconut shell but be never hides there.
Thank you so much for your advice.

 

[Tacocat]

Thank you for your answer. Unfortunately I can't have the plants because if I put the lights on the brown algae will spread all over the aquarium.In just 5 hours the water gets all brownish. I thought my platy could feel lonely but I'm afraid if I get another fish now, he will attack because my platy is weak.
The lava rock was small and it was just because of bacteria he never got close to it or hide under... Only started when his behaviour changed. He has the coconut shell but be never hides there.
Thank you so much for your advice.

you can put the lights on, just try to make them dimmer. a way to do that is by putting etape(electrical tape) on it, so that there's less light. Also, with plants, it will ease the load on the filter as well as taking nutrients from the water, therefore using nitrates and for there to be less nutrients for the algae to use.

Depends on what kind of fish you get for the platy. if it's another platy, it should be fine.

 

[Tacocat]

Do you not want the shrimp to spawn? Don't amano's give birth in brackish?(note: I don't own amanos and never have, don't take my word on this, I just read this somewhere a while ago)

 

[Ignia]

you can put the lights on, just try to make them dimmer. a way to do that is by putting etape(electrical tape) on it, so that there's less light. Also, with plants, it will ease the load on the filter as well as taking nutrients from the water, therefore using nitrates and for there to be less nutrients for the algae to use.

Depends on what kind of fish you get for the platy. if it's another platy, it should be fine.

Hi Tacocat, thank for your answer. I could try to put salvinia again.. The shrimps loved it. I took the plants away because they were getting dark and could create nitrites or ammonia and didn't want to risk it... I don't know wich
Thank you.

 

[Ignia]

Do you not want the shrimp to spawn? Don't amano's give birth in brackish?(note: I don't own amanos and never have, don't take my word on this, I just read this somewhere a while ago)

I didn't think of that . I read that is very difficult for baby amano Shrimps to survive even with right conditions.... But adults it seems that don't like much salt water... That's what I read but I might not be reading the right information.. There's always so much online. She's with 3 weeks... She might have between 1 to 2 more weeks to "deliver".
Thank you for calling my attention that.

 

[Essjay]

Amano eggs hatch to a larval stage unlike most other shrimps. These larvae need salt water and microscopic algae to feed on, which is difficult to replicate in home tanks.

 

[Tacocat]

I took the plants away because they were getting dark and could create nitrites or ammonia and didn't want to risk it... I don't know wich

The plants will not create either of those, but they will in fact remove them. They will also take out nitrates which is helpful if you don't like doing water changes(you should still do it, but it does remove the nitrates). What do you mean darkness???