not exactly right. as following: I caught a fish. 我钓到了一条鱼 （wǒ diào dao le yī tiáo yú） A halibut. 是一条大比目鱼 （shì yī tiáo dà bǐ mù yǘ） It was big. 它很大 (tā hěn dà）

1st, use "，" better than "。" before the sentence end. 2nd, It was big, means the fish is very big, so translate as 这条鱼很大 is correct 3rd, don't forget "。" at the end of sentence. 我钓到了一条鱼，一个大比目鱼，这条鱼很大。

"I caught a fish." translate as 我钓到了一条鱼。（correct) " A halibut." translate as 一个大比目鱼。(wrong) 一条比目鱼（correct) It was big. translate as "这是大"(not exactly right) 它是条大鱼。（correct) if you want to put the three individual sentences into one sentence, then it should be like this 我钓到了一条大比目鱼。

我钓到一条很大的比目鱼，SIMPLE ONE ，呵呵。

In daily speech, we say in this way. 我钓到一条鱼，一条比目鱼，个儿头不小。 You can also say 个儿挺大的！ 这是条大鱼！ 这鱼个儿不小！ 是条大鱼！ ...... 这些都是比较口语化的表达，都是同一个意思。