New tank have questions

[Nedly]

I just got this tank going maybe a week and a half ago. I believe it is 20 gallon, but I cannot be sure. There is no sticker, how can I know for sure? I have a couple questions regarding the tank and a couple fish. For one, I started out with a smaller 5 gallon tank and purchased a 2-10 gallon filter right before upgrading to this tank. Now that I have this tank going, I am wondering if I should get a bigger filter? This 10 gallon filter is keeping the water clean, but I feel like I am going through filters cartridges fast.

Second, there is one fish I got I do not know the type. I forgot. It is the female, yellow platy with some rainbow colors on the sides, about the size of a mollie. Also, I got this green lantern platy yesterday, male, and it has been going rounds with the other fish. I do not know if it is fighting, posturing, or just teasing. They get into these nipping matches where they spin in "ying and yang" circles nipping at each other. The goblin started out targeting my black mollie which did not go well because my mollie is a big beast.

Then the lantern platy started teasing another male mollie. Then today, it has started teasing the unidentified platy with the yellow. So far the only fish showing any damage is the lantern platy with a small red scrape under his side fin, but I cannot say whether it was there when I got him or not.

I am also curious to an issue I faced with a couple of my first fish. One of my very first was a dalmatian mollie that came out of the store sick, it always let its rear fin drag and never really used it. It died, and then later I got a white mollie that did the same thing. From the store these fish were sick and I have not had the issue with any other fish. What is the main cause for a fish to stop using its rear fin and die? It is part of the "shimmy"?

Any help, info, suggestions would be great. I think I got it all right, I got pretty much everything I could as far as tank supplies from bacteria supplement from when it was a new tank, water conditioner, ph balance, the filter, oxygen, aquarium salt...

 

[Nedly]

This is my list of fish. I don't know but maybe they are fighting over the female? The female is the undetermined platy fish. All the rest are males.

3 mollies all males
-2 red, 1 black
3 platy fish with 1 female
-bumble bee platy, green lantern platy, and undetermined platy
2 small bottom feeders
1 red tailed shark

9 fish total. 20 gallon tank. All males except the one female. As far as the bottom feeders I do not know their sex, and the red tailed shark is a loner. Are their any signs to the mating process between the platys? Will the males fight for the female?

 

[posenergy]

If it is 20g you have too many fish in there. They are probably a little stressed so that's why they fight.

This tank looks a little more than 20 to me though.. So maybe your theory about why they fight is more accurate.


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[posenergy]

Also.. Filter cartridges can last a little longer than advertised. You can clean and re use them once or twice.


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[Nedly]

How would you suggest washing the filters? I tried that at first but the used filter was so clogged the water was pouring over the top of it and was only like a week or so old. I said w/e and ordered one today, I figured may as well have the right size and keep the little one around in case I need a separate tank for babies.

What is the suggested fish population per gallon? When I first went fish shopping the aquatic worker said "no more than 4-fish in a 4-gallon" so I assumed a fish per gallon (which I would find ridiculous) I do not intend to exceed 10 in this specific tank, but it would be good to know what level of population is good!

 

[Nedly]

Are mirrored tanks bad for fish? This one is hex and three of the back panes are mirrored, I noticed they swim up and down with their reflection. I have a 50 gallon tank on a stand I am thinking about setting up now. I have been all over this forum and I think I may need to up my game a little for some happy fish..

 

[Pamiam]

Here is my 2 cents for whats it is worth.

You could have issues with mostly all males in the tank, males want females. My ratio I keep is 1 male with 4-5 females, this is so my females are not stressed by too much attention.

Second Mollies should be in brackish water for premium health...yes you can keep them in normal freshwater, but their bodies are made for brackish water.

And the red tail shark should be housed in a minimum 50 gallon tank and he is a loner but territorial. They say they grow to 4 inches but mine is 7 inches.

Then the hex tank has low surface volume which means less oxygen exchange, which could be an issue.

As for fish ratio per gallon...I never go by that reasoning. I go by the fish, their characteristics and compatibility.

you have to consider who schools, who are fin nippers, who likes to live alone and what part of the aquarium do they inhabit

 

[Nedly]

Thank you for the information! I am a little new to it all but I am figuring it out. I did make the water brackish, I got the "aquarium salt" and put in the recommended amount.

As far as a bigger tank, I have a 50 gallon in storage I am pulling out within the next couple days, I ordered a good filter for it and it should ship in a week. I did not know the shark got that big! The store said minimum 20 gallons for up to 4", I have to say if it gets to 7" I will be stoked.

Also, I did not think much about having too many males vs females. When I started purchasing fish I did not know how to tell the difference. I am working on correcting it all now, and everyones help has been grand.

I started with a 1 gallon with a couple fish and they hated the tank, so I upped it to 4 gallon. They hated that tank, so I set up the 20 gallon hex, and now, well, it is not the best, so onto the 50 gallon tank I guess. I went from 1 gallon to 50 in a month. I want to do it right : )

 

[Pamiam]

I hope you have fun with this hobby, there is a lot to learn but the rewards far out weigh the trouble.

In my opinion...I think all fish should be in a 50+ tank, they like to swim...they are fish...it is their nature.

2 short stories here...to encourage you I hope.

I have my shark trained to play hide and seek, they are curious by nature and in my opinion very smart. I have many cave like decorations...when I tap on a certain area....she goes into that decoration and peaks out I tap near another decoration and she goes to that and peaks in and out. The grandkids love to play with her in that manner.

I have had fish for 10 years and my background is a biologist and teacher. I have a lot of back ground in marine biology, but I still make a lot of mistakes.

Just this week I bought 5 pineapple swordtails. (1 male, 4 females) I want them to breed so I can use their off spring for snacks for my larger fish. Fish eat fish in nature and it is more to maintain a healthy diet. These fish are 2 inches long right now so I put them in my tank with my Ctenopoma acutirostre who is 5 inches. The next morning Mr. Ctenopoma apparently could not wait for the babies and tried to eat one of the swordtails. I did not think he could swallow a fish that large....opps!

Just to show I am still making mistakes

Good Luck with your tank.

Oh ... a side note...brackish water has marine salt, not aquarium salt. Aquarium salt is for a balance of electrolytes and other health benefits. However scaleless fish such as corys can not tolerate much salt at all. I only add 2 tablespoons in my 55 gallon.